Heat transfer fluids and methods of use

ABSTRACT

This disclosure relates to heat transfer fluids for use in heat transfer systems. The heat transfer fluids comprise at least one non-aqueous dielectric heat transfer fluid. The non-aqueous dielectric heat transfer fluid has density (ρ), specific heat (c p ), and dynamic viscosity (μ) properties. The heat transfer fluids have a normalized effectiveness factor (NEF fluid ) as determined by the following equation: 
     
       
         
           
             
               
                 N 
                 ⁢ 
                 E 
                 ⁢ 
                 
                   F 
                   fluid 
                 
               
               = 
               
                 
                   DEF 
                   fluid 
                 
                 
                   DEF 
                   reference 
                 
               
             
             ; 
           
         
       
     
     wherein DEF fluid  is a dimensional effectiveness factor for the heat transfer fluid that is determined based on an equation designated in Table 1 below for a selected pump and a selected heat transfer circuit dominant flow regime; wherein DEF reference  is a dimensional effectiveness factor for a reference fluid that is determined using the same equation designated in Table 1 for DEF fluid  above for the same selected pump and the same selected heat transfer circuit dominant flow regime; and 
                 TABLE 1           (Heat Transfer Fluid and Reference Fluid)                   Selected Heat         Transfer Circuit         Flow Regime                           Transition     Selected Pump   Laminar   (Blasius)           Positive Displacement Pump   ρ 1  c p   1  μ −1     ρ 0.25  c p   1  μ −0.25       Centrifugal Pump   ρ 0.19  c p   1  μ −0.19     ρ 0.04  c p   1  μ −0.04                                                
wherein the heat transfer fluid has a NEF fluid  value equal to or greater than 1.0. This disclosure also provides a method for improving performance of a heat transfer system, a method for improving performance of an apparatus, and a method for selecting a heat transfer fluid for use in a heat transfer system. The heat transfer fluids and methods of this disclosure are applicable in situations where the heat transfer system is dominated by heat conveyance.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 62/863,385 filed Jun. 19, 2019, which is herein incorporated byreference in its entirety.

FIELD

This disclosure provides heat transfer fluids for use in electricalapparatuses, in particular, electric vehicles, batteries, server banks,and data centers. This disclosure also provides a method for improvingperformance of an electrical apparatus heat transfer system, a methodfor to improving performance of an electrical apparatus, and a methodfor selecting a heat transfer fluid for use in an electrical apparatusheat transfer system. The heat transfer fluids and methods of thisdisclosure are applicable in situations where the heat transfer systemis dominated by heat conveyance.

BACKGROUND

A major challenge in cooling electric vehicles as well as mechanical andelectrical systems, subsystems and components for electric vehicles, isformulating fluids with satisfactory heat transfer performance inspecific devices. In particular, the challenge in heat transfer fluidsis formulating fluids with satisfactory heat transfer performance inspecific devices, and also having compatibility with electric vehiclecomponents and materials.

The removal of heat from electric vehicle components such as batteriesand electric motors during electric vehicle operation is commonly doneusing aqueous heat transfer fluids, which indirectly remove heat fromthe hot surfaces. As electric vehicle technology evolves to comprehendlonger battery ranges, shorter recharging times, and higher vehiclepower, there will be benefits associated with direct cooling of hotcomponents, which is not possible with aqueous heat transfer fluids.

For example, direct cooling is significantly more efficient in emergencysituations like run away reactions inside battery cells. The faster heatremoval allows for improved thermal management where battery cells willnot reach critical temperatures that can lead to irreversible batteryfires. Indirectly cooled systems (e.g., water/glycol) are limited by thethermal conductivity of the jacket. Fast heat removal is a major benefitof a directly cooled system. Fast heat removal is also needed, forexample, during super fast charging of lithium ion batteries.

In many electric vehicle applications, the performance of a heattransfer fluid is governed both by its ability to remove heat from hotsurfaces and by the amount of power required to circulate the heattransfer fluid. An ideally-suited heat transfer fluid will maximize heatremoval and require minimum power to circulate the fluid.

A Mouromtseff equation is used in the art for comparing the impact ofheat transfer fluid properties on the resulting heat transfercoefficient. The Mouromtseff equation for turbulent flow systems isdefined as follows: k^(0.67)*ρ^(0.8)*c_(p) ^(0.33)*μ^(−0.47); and forlaminar flow systems is defined as follows: While the use of theMouromtseff equation provides a convenient method for quickly comparingheat transfer fluids, its use has a number of short comings. Forexample, use of the Mouromtseff equation implies that heat transfer inthe physical situation in which the fluid is to be used is limited byheat transfer. In some situations (for example, if large heat transferareas exist at the element to be cooled and the heat rejection site),heat conveyance by the circulating fluid may dominate. In such asituation, the actual mechanism of local heat transfer, and thereforefluid property impacts on that heat transfer, become significantlydiminished. In these applications, while the Mouromtseff equation may beindicating something about the fluid, what it is indicating issignificantly less relevant to its heat transfer performance.

Despite advances in heat transfer fluid formulation technology inelectric vehicles, there exists a need for formulating fluids withsatisfactory heat transfer performance in specific devices. Also, thereis a need for heat transfer fluid formulations having compatibility withspecific device components and materials. Further, there exists a needfor heat transfer fluids that can maximize heat removal and requireminimum power to circulate. Still further, an improved method forquickly and conveniently comparing heat transfer fluids and heattransfer that addresses operating variables, in addition to heattransfer fluid properties, in heat conveyance dominated situations, isneeded.

SUMMARY

This disclosure relates to formulating fluids with satisfactory heattransfer performance in specific devices, e.g., electric vehicles,electric motors, batteries, electronics, computers, server banks, anddata centers. The heat transfer fluid formulations of this disclosurehave compatibility with specific device components and materials. Theheat transfer fluid formulations maximize heat removal and requireminimum power to circulate in specific device heat transfer systems.This disclosure relates to a method for quantitatively comparing heattransfer fluids and heat transfer that addresses operating variablessuch as circulation system flow regimes and types of pumps, in additionto heat transfer fluid properties, in heat conveyance dominatedsituations.

This disclosure also relates in part to a method for improvingperformance of a heat transfer system. The method comprises: (i)providing an apparatus having a heat transfer system, the heat transfersystem comprising a heat transfer circuit, where the heat transfercircuit comprises: a pump, a conduit, and a heat exchanger; wherein thepump is at least one pump selected from a positive displacement pump anda centrifugal pump; (ii) circulating at least one non-aqueous dielectricheat transfer fluid through the heat transfer circuit to transfer heatwith the apparatus, the non-aqueous dielectric heat transfer fluidhaving density (ρ), specific heat (c_(p)), and dynamic viscosity (μ)properties; wherein the heat transfer fluid circulating through the heattransfer circuit has a heat transfer circuit dominant flow regimeselected from laminar flow and transition flow; wherein the heattransfer system is heat conveyance dominated; and (iii) determining anormalized effectiveness factor (NEF_(fluid)) of the heat transfer fluidfrom the following equation:

${{NEF_{fluid}} = \frac{{DEF}_{fluid}}{{DEF}_{reference}}};$wherein DEF_(fluid) is a dimensional effectiveness factor for the heattransfer fluid that is determined based on an equation designated inTable 1 below for a selected pump and a selected heat transfer circuitdominant flow regime; wherein DEF_(reference) is a dimensionaleffectiveness factor for a reference fluid that is determined using thesame equation designated in Table 1 for DEF_(fluid) above for the sameselected pump and the same selected heat transfer circuit dominant flowregime; wherein DEF_(fluid) and DEF_(reference) are determined at apredetermined temperature in an apparatus heat transfer application, andmatching units for each property are used in each equation; and

TABLE 1 (Heat Transfer Fluid and Reference Fluid) Selected Heat TransferCircuit Flow Regime Transition Selected Pump Laminar (Blasius) PositiveDisplacement Pump ρ¹ c_(p) ¹ μ⁻¹ ρ^(0.25) c_(p) ¹ μ^(−0.25) CentrifugalPump ρ^(0.19) c_(p) ¹ μ^(−0.19) ρ^(0.04) c_(p) ¹ μ^(−0.04)whereby performance of the heat transfer system during operation isimproved using a heat transfer fluid having a NEF_(fluid) value equal toor greater than 1.0.

This disclosure further relates in part to a method for improvingperformance of an apparatus. The method comprises: (i) providing anapparatus having a heat transfer system the heat transfer systemcomprising a heat transfer circuit, where the heat transfer circuitcomprises: a pump, a conduit, and a heat exchanger; wherein the pump isat least one pump selected from a positive displacement pump and acentrifugal pump; (ii) circulating at least one non-aqueous dielectricheat transfer fluid through the heat transfer circuit to transfer heatwith the apparatus, the non-aqueous dielectric heat transfer fluidhaving density (ρ), specific heat (c_(p)), and dynamic viscosity (μ)properties; wherein the heat transfer fluid circulating through the heattransfer circuit has a heat transfer circuit dominant flow regimeselected from laminar flow and transition flow; wherein the heattransfer system is heat conveyance dominated; and (iii) determining anormalized effectiveness factor (NEF_(fluid)) of the heat transfer fluidfrom the following equation:

${{NEF_{fluid}} = \frac{{DEF}_{fluid}}{{DEF}_{reference}}};$wherein DEF_(fluid) is a dimensional effectiveness factor for the heattransfer fluid that is determined based on an equation designated inTable 1 below for a selected pump and a selected heat transfer circuitdominant flow regime; wherein DEF_(reference) is a dimensionaleffectiveness factor for a reference fluid that is determined using thesame equation designated in Table 1 for DEF_(fluid) above for the sameselected pump and the same selected heat transfer circuit dominant flowregime; wherein DEF_(fluid) and DEF_(reference) are determined at apredetermined temperature in an apparatus heat transfer application, andmatching units for each property are used in each equation; and

TABLE 1 (Heat Transfer Fluid and Reference Fluid) Selected Heat TransferCircuit Flow Regime Transition Selected Pump Laminar (Blasius) PositiveDisplacement Pump ρ¹ c_(p) ¹ μ⁻¹ ρ^(0.25) c_(p) ¹ μ^(−0.25) CentrifugalPump ρ^(0.19) c_(p) ¹ μ^(−0.19) ρ^(0.04) c_(p) ¹ μ^(−0.04)whereby performance of the apparatus during operation is improved usinga heat transfer fluid having a NEF_(fluid) value equal to or greaterthan 1.0.

This disclosure yet further relates in part to a method for selecting aheat transfer fluid for use in a heat transfer system. The methodcomprises: (i) providing an apparatus having a heat transfer system, theheat transfer system comprising a heat transfer circuit, where the heattransfer circuit comprises: a pump, a conduit, and a heat exchanger;(ii) circulating at least one non-aqueous dielectric heat transfer fluidthrough the heat transfer circuit to transfer heat with the apparatus,the non-aqueous dielectric heat transfer fluid having density (ρ),specific heat (c_(p)), and dynamic viscosity (μ) properties; (iii)selecting a type of pump used in the heat transfer circuit, wherein thepump is at least one pump selected from a positive displacement pump anda centrifugal pump; (iv) selecting a heat transfer circuit dominant flowregime used to circulate the heat transfer fluid through the heattransfer circuit; wherein the heat transfer circuit dominant flow regimeis selected from laminar flow and transition flow; (v) conducting theapparatus heat transfer system such that it is heat conveyancedominated; (vi) determining a normalized effectiveness factor(NEF_(fluid)) for the heat transfer fluid from the following equation:

${{NEF_{fluid}} = \frac{{DEF}_{fluid}}{{DEF}_{reference}}};$wherein DEF_(fluid) is a dimensional effectiveness factor for the heattransfer fluid that is determined based on an equation designated inTable 1 below for the selected pump and the selected heat transfercircuit dominant flow regime; wherein DEF_(reference) is a dimensionaleffectiveness factor for a reference fluid that is determined using thesame equation designated in Table 1 for DEF_(fluid) above for the sameselected pump and the same selected heat transfer circuit dominant flowregime; wherein DEF_(fluid) and DEF_(reference) are determined at apredetermined temperature in an apparatus heat transfer application, andmatching units for each property are used in each equation; and

TABLE 1 (Heat Transfer Fluid and Reference Fluid) Selected Heat TransferCircuit Flow Regime Transition Selected Pump Laminar (Blasius) PositiveDisplacement Pump ρ¹ c_(p) ¹ μ⁻¹ ρ^(0.25) c_(p) ¹ μ^(−0.25) CentrifugalPump ρ^(0.19) c_(p) ¹ μ^(−0.19) ρ^(0.04) c_(p) ¹ μ^(−0.04)(vii) selecting the heat transfer fluid for use in the heat transfersystem if the NEF_(fluid) for the heat transfer fluid is a value equalto or greater than 1.0.

This disclosure also relates in part to a heat transfer fluid for use ina heat transfer system. The heat transfer fluid comprises: at least onenon-aqueous dielectric heat transfer fluid, the non-aqueous dielectricheat transfer fluid having density (ρ), specific heat (c_(p)), anddynamic viscosity (μ) properties; wherein the heat transfer systemcomprises an apparatus and a heat transfer circuit, where the heattransfer circuit comprises: a pump, a conduit, and a heat exchanger;wherein the pump is at least one pump selected from a positivedisplacement pump and a centrifugal pump; wherein the heat transferfluid circulating through the heat transfer circuit has a heat transfercircuit dominant flow regime selected from laminar flow and transitionflow; wherein the heat transfer system is heat conveyance dominated; andwherein the heat transfer fluid has a normalized effectiveness factor(NEF_(fluid)) as determined by the following equation:

${{NEF_{fluid}} = \frac{{DEF}_{fluid}}{{DEF}_{reference}}};$wherein DEF_(fluid) is a dimensional effectiveness factor for the heattransfer fluid that is determined based on an equation designated inTable 1 below for a selected pump and a selected heat transfer circuitdominant flow regime; wherein DEF_(reference) is a dimensionaleffectiveness factor for a reference fluid that is determined using thesame equation designated in Table 1 for DEF_(fluid) above for the sameselected pump and the same selected heat transfer circuit dominant flowregime; wherein DEF_(fluid) and DEF_(reference) are determined at apredetermined temperature in an apparatus heat transfer application, andmatching units for each property are used in each equation; and

TABLE 1 (Heat Transfer Fluid and Reference Fluid) Selected Heat TransferCircuit Flow Regime Transition Selected Pump Laminar (Blasius) PositiveDisplacement Pump ρ¹ c_(p) ¹ μ⁻¹ ρ^(0.25) c_(p) ¹ μ^(−0.25) CentrifugalPump ρ^(0.19) c_(p) ¹ μ^(−0.19) ρ^(0.04) c_(p) ¹ μ^(−0.04)wherein the heat transfer fluid has a NEF_(fluid) value equal to orgreater than 1.0.

It has been surprisingly found that the effectiveness of a heat transferfluid is highly dependent on the design of the apparatus to be heatmanaged, and in some cases, certain properties of the heat transferfluid are irrelevant. In other cases, the heat transfer fluid propertiesare relevant but to various extents, as reflected by various exponentsin the DEF equations above. Also, it has been surprisingly found, inaccordance with this disclosure, how heat flow and power to circulatethe heat transfer fluid, and as a result the fluid's effectiveness in anapparatus application, are impacted by heat transfer fluid properties. Aunique combination of heat transfer fluid properties has been identifiedthat maximize effectiveness for the apparatus designs taking intoaccount operating variables such as circulation system flow regimes andtypes of pumps, and also situations where heat conveyance dominates, asdescribed herein. This unique combination of fluid properties, which isreferred to as the normalized effectiveness factor (NEF_(fluid)) of theheat transfer fluid, has been found to differ from the combination offluid properties proposed in the industry as generally applying withrespect to heat transfer with liquid coolants, known as the Mouromtseffequation. As a result, for fluids with properties yielding highernormalized effectiveness factor (NEF_(fluid)) values than comparativematerials with lower normalized effectiveness factor (NEF_(fluid))values, the overall performance of the heat transfer system can beoptimized.

In particular, it has been surprisingly found that, in accordance withthis disclosure, improvement in performance of a heat transfer system isobtained by using a heat transfer fluid having a normalizedeffectiveness factor (NEF_(fluid)) equal to or greater than 1.

Other objects and advantages of the present disclosure will becomeapparent from the detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows formulations and properties, dimensional effectivenessfactor (DEF_(fluid)) values, and normalized effectiveness factor(NEF_(fluid)) values, for reference fluids and heat transfer fluids at atemperature of 40° C., where heat conveyance is the dominant mechanismcontrolling performance of the reference fluid and heat transfer fluidin an application.

FIG. 2 shows formulations and properties, dimensional effectivenessfactor (DEF_(fluid)) values, and normalized effectiveness factor(NEF_(fluid)) values, for reference fluids and heat transfer fluids at atemperature of 80° C., where heat conveyance is the dominant mechanismcontrolling performance of the reference fluid and heat transfer fluidin an application.

FIG. 3 is a block diagram of a computer related system for use indetermining dimensional effectiveness factor (DEF_(fluid)) values andnormalized effectiveness factor (NEF_(fluid)) values, in accordance withthis disclosure.

FIG. 4 depicts a schematic of an illustrative heat transfer circuit inaccordance with this disclosure.

DETAILED DESCRIPTION Definitions

“About” or “approximately”. All numerical values within the detaileddescription and the claims herein are modified by “about” or“approximately” the indicated value, and take into account experimentalerror and variations that would be expected by a person having ordinaryskill in the art.

“Major amount” as it relates to components included within the heattransfer fluids of the specification and the claims means greater thanor equal to 50 wt. %, or greater than or equal to 60 wt. %, or greaterthan or equal to 70 wt. %, or greater than or equal to 80 wt. %, orgreater than or equal to 90 wt. %, based on the total weight of the heattransfer fluid.

“Minor amount” as it relates to components included within the heattransfer fluids of the specification and the claims means less than 50wt. %, or less than or equal to 40 wt. %, or less than or equal to 30wt. %, or greater than or equal to 20 wt. %, or less than or equal to 10wt. %, or less than or equal to 5 wt. %, or less than or equal to 2 wt.%, or less than or equal to 1 wt. %, based on the total weight of theheat transfer fluid.

“Essentially free” as it relates to components included within the heattransfer fluids of the specification and the claims means that theparticular component is at 0 weight % within the heat transfer fluid, oralternatively is at impurity type levels within the heat transfer fluid(less than 100 ppm, or less than 20 ppm, or less than 10 ppm, or lessthan 1 ppm).

All percentages in describing heat transfer fluids herein are by weightunless specified otherwise. “Wt. %” means percent by weight.

“Electric vehicle(s)” refer to in this disclosure as all-electric andfully electric vehicles, and hybrid and hybrid electric vehicles, andincludes the mechanical and electrical systems, subsystems, andcomponents having gears used in the vehicles. These mechanical andelectrical systems, subsystems and components having gears can include,for example, electrical vehicle powertrains, powertrain components,drivetrain components, kinetic energy recovery systems (KERS), energyregenerative systems, and the like. The terms electric vehicle andhybrid vehicle may be used interchangeably. In this disclosure, thephrase “electric vehicle” includes hybrid and hybrid electric vehicles,which may have any of a variety of parallel or series drivetrainconfigurations, alone or in combination.

It has now been found that the removal of heat from components such asbatteries, on-board power electronics, super fast charging systems, andelectric motors during electric vehicle operation can be done usingnon-aqueous heat transfer fluids, which directly removes heat from thehot surfaces. As electric vehicle technology evolves to comprehendlonger battery ranges, shorter recharging times, and higher vehiclepower, there will be benefits associated with direct cooling of hotcomponents (including weight reduction do to engineering design changes,or due to the reduction of the mass contribution from the heat transferfluid), which is not possible with aqueous heat transfer fluids. Inaddition, the use of non-aqueous dielectric coolants in accordance withthis disclosure can reduce the possibility of safety issues associatedwith the electrical conductivity of water, including potential risk ofhydrogen formation and release. Non-aqueous heat transfer fluids (e.g.,hydrocarbon-based heat transfer fluids) can provide benefits in theevolving electric vehicle application with respect both to directcooling of hot component surfaces and safety based on their lowelectrical conductivity.

In an electric vehicle application, the performance of a heat transferfluid is governed both by its ability to remove heat from hot surfacesand by the amount of power required to circulate the heat transferfluid. The heat transfer fluids of this disclosure maximize heat removaland require minimum power to circulate. Depending on the design of theelectric vehicle, it has been found that the heat transfer fluidproperties that govern its overall performance differ. For example, inan electric vehicle design where there is a very large surface areaacross which heat is to be removed from hot surfaces, and a very largesurface area across which heat in turn removed from the heat transferfluid to lower its temperature before recirculation, the heat capacityof the heat transfer fluid will dominate in determining the amount ofheat flow from the hot components to the heat transfer fluid. In otherelectric vehicle designs, heat transfer fluid properties such asviscosity, density, and thermal conductivity also play key roles indetermining the heat flow. In each case, the properties of the heattransfer fluid have been found to be important in determining the amountof power required to circulate the heat transfer fluid.

The overall effectiveness of a heat transfer fluid in a given electricvehicle design can be defined as the ratio of heat flow to the power tocirculate the heat transfer fluid.

It has been found that an electric vehicle heat transfer fluid with ahigher effectiveness will be able to remove more heat from hot surfacesper amount of power required to circulate the fluid. This will enablesignificant benefits in terms of maximizing electric vehicle batteryrange and/or optimizing the design of the heat transfer system in thevehicle. By evaluating the electric vehicle design parameters, it hasbeen determined how heat flow and power to circulate the heat transferfluid, and as a result the fluid's effectiveness in this electricvehicle application, are impacted by heat transfer fluid properties. Aunique combination of fluid properties has been identified that maximizeeffectiveness for the electric vehicle designs described herein.

In an embodiment, a larger electric device may be made up of severalsmaller devices that perform according to different regimes. Differentheat transfer fluids may be needed for the smaller devices that performaccording to different regimes (e.g., batteries, front motors, rearmotors, power management systems, electronics controlling a battery,on-board power electronics, super fast charging systems, fast chargingequipment at charging stations, stationary super fast chargers, oron-board chargers). In accordance with this disclosure, methods forselecting particular heat transfer fluids for particular components areprovided. In some cases, the selection of heat transfer fluids fordifferent components can be contradictory, which means that in someinstances involving a larger electrical device, multiple heat transferfluids may be optimal or a trade-off may need to be made so that asingle heat transfer fluid is selected as the best for the most powerintensive component, and that same selected fluid is less optimal forother components, but the overall performance is more optimal than if analternate fluid is selected.

In accordance with this disclosure, it has been found that this uniquecombination of fluid properties, which is referred to as the normalizedeffectiveness factor (NEF_(fluid)) of the heat transfer fluid, differsfrom the combination of fluid properties proposed in the industry asgenerally applying with respect to heat transfer with liquid coolants,known as the Mouromtseff equation, which is defined as follows forturbulent flow systems: k^(0.67)*ρ^(0.8)*c_(p) ^(0.33)*μ^(−0.47); andfor laminar flow systems is defined as follows: V. As a result, for heattransfer fluids with properties yielding higher normalized effectivenessfactor (NEF_(fluid)) values than comparative materials with lowernormalized effectiveness factor (NEF_(fluid)) values, the overallperformance of a heat transfer system can be optimized.

The Mouromtseff equation referred to herein was developed as a quick andconvenient method for comparing the impact of fluid properties on theresulting heat transfer coefficient. While the use of the Mouromtseffequation provides a convenient method for quickly comparing fluids, itsuse has a number of short comings, for example, with respect to flowrate, dimensionality, and dominant heat conveyance mechanism.

With respect to flow rate, in eliminating all of the variables from heattransfer correlations except those to do with fluid physical properties,the traditional Mouromtseff equation derivation ignores any impact thatthe fluid properties may have on the fluid circulation rate. Inparticular, if a centrifugal pump is being used, it is well known thatthe fluid properties could impact the circulation rate, and thereforethe local fluid velocity. Thus a variable is typically eliminated, whenit itself has dependence on the fluid properties. This dependency shouldbe included in any fluid comparison.

With respect to dimensionality, in the use of the traditionalMouromtseff equation, the fluid property variables have units. Thismeans that unlike the Nusselt (Nu), Reynolds (Re), and Prandlt (Pr)numbers, the resulting Mouromtseff equation is not dimensionless,however the appropriate units are frequently not reported in theliterature. Therefore, any two different practitioners who calculate aMouromtseff equation for the same fluid may produce different numbers,depending on, for example, if one uses Si units, and the other usesimperial units.

The Nusselt (Nu), Reynolds (Re), and Prandlt (Pr) numbers are defined asfollows:

${Nu} - {{Nusselt}\mspace{14mu}{number}\mspace{14mu}\left( {{Nu} = \frac{hd}{k}} \right)}$

${Re} - {{Reynolds}\mspace{14mu}{number}\mspace{14mu}\left( {{Re} = \frac{d\; v\;\rho}{µ}} \right)}$

$\Pr - {{Prandlt}\mspace{14mu}{number}\mspace{14mu}\left( {\Pr = \frac{c_{p}µ}{k}} \right)}$wherein μ_(Bulk) is average bulk fluid viscosity, μ_(Surface) is averagesurface fluid viscosity, h is fluid heat transfer coefficient, d is flowdiameter, k is average fluid thermal conductivity, v is fluid velocity,μ is average fluid viscosity, and c_(p) is average fluid heat capacity.

With respect to dominant heat transfer mechanism, use of the Mouromtseffequation implies that heat removal in the physical situation in whichthe fluid is to be used is dominated by localized heat transfer. In somesituations (for example, if large heat transfer areas exist at theelement to be cooled and the heat rejection site), heat conveyance bythe circulating fluid may dominate. In such a situation, the actualmechanism of local heat transfer, and therefore fluid property impactson that heat transfer, become irrelevant. In these applications, whilethe Mouromtseff equation may be indicating something about the fluid,what is indicating is irrelevant to the fluid performance as a heattransfer fluid.

Power is required to circulate the heat transfer fluid. For some heattransfer applications where this power is independently supplied, thismay not be an issue. However particular in mobility applications, thispower to circulate the fluid is often provided by the same power sourcethat provides the power for the mobility. For example, in an electricvehicle, the battery provides the power for vehicle motion, and thepower for circulating the heat transfer fluid. A similar situationoccurs in aeronautical and aerospace applications. In such situations,when comparing fluids for heat transfer service, one needs to considerboth how the fluid properties impact heat transfer, and how the fluidproperties impact the power required to circulate the fluid.

The power required to circulate the fluid is simply the product of thefluid volumetric flowrate and the pressure drop through the circulatingcircuit. This does not include any inefficiencies of the specific pumpperforming this circulating power, and is assumed to be delivered by anideal pump. The fluid properties impact on both the volumetric flowrateof the circulating fluid, and the pressure drop through the circuit willbe dependent on what flow regime dominates pressure drop in thatcircuit. The presence of laminar, transitional, or turbulent lead todifferent relationships.

Equally, the specific type of pump being used to circulate the fluidwill have an impact. For an ideal positive displacement pump, thevolumetric flowrate will always be constant, regardless of fluidproperties, but the resulting pressure drop will be impacted byproperties. In that situation, the localized heat transfer dominance andheat conveyance dominance will both not change due to flowrate, but thepumping power will still vary for different fluids. On the contrary, ifa constant pressure pump were to be used (i.e., a pump circulationsystem where the delivery pressure was constant, regardless offlowrate), the flowrate would change with physical properties, as wouldtherefore the power required to circulate the fluid. For a centrifugalpump, both the delivered pressure and the volumetric flow could changewith different fluids.

In accordance with this disclosure, a new effectiveness factor has beendeveloped that considers both the fluid's performance as a heat transfermedium, and the power required to circulate the fluid. This factor willdepend on the specific application, depending on whether heat transferwithin the element to be cooled dominates or whether heat conveyance bythe circulating fluid dominates (typically because of relatively largeheat transfer areas, or low circulation rates are used). It is referredto as a dimensional effectiveness factor (DEF_(fluid)) because it willhave the same deficiency as the Mouromtseff equation. It will haveunits, making its specific value dependent on the units used for thespecific properties.

When heat conveyance is the dominant mode controlling performance of theheat transfer fluid in an application, the dimensional effectivenessfactor (DEF_(fluid)) dependencies on fluid properties for the specifiedfluid circulation flow regimes and pump types are given in Table 1herein. Table 1 gives dimensional effectiveness factor (DEF_(fluid))equations for situations where heat conveyance is the dominant mechanismcontrolling performance of the heat transfer fluid in an application. InTable 1, the specifics of the heat transfer are not relevant, since theydo not control the fluid's heat transfer performance. Thus, the fluidcould be flowing through tubes, or over flat plates, or being sprayed asa jet, or any other fluid contact mechanism, and because the heatconveyance is dominant, the applicable dimensional effectiveness factor(DEF_(fluid)) equation from Table 1 would apply. Since the local heattransfer mechanism is not important, it can be seen that the fluid'sthermal conductivity does not appear in Table 1 for any of the cases.

To overcome the issue of the dependence of the dimensional effectivenessfactor (DEF_(fluid)) on the units system being used, a normalizedeffectiveness factor (NEF_(fluid)) is used in this disclosure. Thenormalized effectiveness factor (NEF_(fluid)) is given by:

${{NEF}_{fluid} = \frac{{DEF}_{fluid}}{{DEF}_{reference}}};$wherein DEF_(fluid) is a dimensional effectiveness factor for the heattransfer fluid that is determined based on an equation designated inTable 1 herein for a selected pump and a selected heat transfer circuitdominant flow regime; and wherein DEF_(reference) is a dimensionaleffectiveness factor for a reference fluid that is determined using thesame equation designated in Table 1 for DEF_(fluid) above for the sameselected pump and the same selected heat transfer circuit dominant flowregime. Both DEF_(fluid) and DEF_(reference) are determined at the samepredetermined temperature, and matching units for each property are usedin each equation.

The predetermined temperature for determining DEF_(fluid) andDEF_(reference) can vary over a wide range. For example, thepredetermined temperature can be between about −40° C. and about 175°C., or between about −25° C. and about 170° C., or between about −10° C.and about 165° C., or between about 0° C. and about 160° C., or betweenabout 10° C. and about 155° C., or between about 25° C. and about 150°C., or between about 25° C. and about 125° C., or between about 30° C.and about 120° C., or between about 35° C. and about 115° C., or betweenabout 35° C. and about 105° C., or between about 35° C. and about 95°C., or between about 35° C. and about 85° C. Preferred predeterminedtemperatures for determining DEF_(fluid) and DEF_(reference) include 40°C. or 80° C.

The properties of a reference fluid DEF_(reference) are readilyavailable in the literature, and provided consistent units are used forevaluation of the DEF_(fluid) and DEF_(reference), the NEF_(fluid) willbe dimensionless, thus eliminating one of the short comings of theDEF_(fluid) and such measures as the Mouromtseff equation.

For any specific application, the appropriate density (ρ), specific heat(c_(p)), and dynamic viscosity (μ) properties can be determined, thenthose properties can be used to calculate the DEF_(fluid) and theDEF_(reference), from which the NEF_(fluid) can be determined.

The fluid properties that the normalized effectiveness factor(NEF_(fluid)) depends on are all temperature dependent. For purposes ofthis disclosure, the properties should be evaluated at the averagetemperature in the element to be cooled. For the use of the equations todefine a fluid, a temperature of 40° C. or 80° C. can be used, howeverany other temperature can be used, provided that the same temperature isused for both the fluid being evaluated, and for the properties of thereference fluid.

In accordance with this disclosure, the normalized effectiveness factor(NEF_(fluid)) equation has a number of benefits, compared to the use ofthe Mouromtseff equation, for evaluating fluids for heat transferapplications.

The primary benefit of the normalized effectiveness factor (NEF_(fluid))equation, compared to the use of the Mouromtseff equation, is thenormalized effectiveness factor (NEF_(fluid)) equation's considerationof the power required to circulate the fluid when evaluating the fluid'spotential heat transfer performance. The normalized effectiveness factor(NEF_(fluid)) equation can be thought of as providing a measure of theheat transfer potential per unit of fluid circulating energy. Forapplications where the power supply is shared between circulating thefluid and providing other uses, minimization of the power required forcirculation will maximize the power available for other purposes. Forexample, if the application is an electric vehicle, having less powerrequired for fluid circulation means that the range available from afully charged battery increases. For a given application, this increasedrange would also lead to an increased battery life, as less chargecycling of the battery would be required. It is also appreciated thateven when the power supply is not used to power other uses, there arestill sufficient power stored.

Alternately, if utilized during the design process, a similar rangecould be produced using a smaller battery. Alternately, the vehicledesigner could utilize the added power to provide additional poweredfeatures on the vehicle. Similarly, in an aeronautical application, thereduced circulating power could lead to improved fuel economy, anincrease range, or additional features being installed on the aircraft.In an aerospace application, power is typically provided via solarcollectors. This limitation on the available power places a greateremphasis on power management and use of the normalized effectivenessfactor (NEF_(fluid)) equation provides a means of obtaining the maximumamount of heat transfer for the limited amount of available circulatingpower.

The traditional derivation of the Mouromtseff equation ignores theimpact of fluid properties on the velocity during the simplification ofthe heat transfer correlations. While this is less important forapplications where a positive displacement is used to circulate thefluid, it is important for other pump types. The normalizedeffectiveness factor (NEF_(fluid)) equation approach ensures that thefluid properties are fully encompassed in the analysis.

Historic use of the Mouromtseff equation leads to use of numbers whichhave units. Comparison of values with different units is not straightforward. Because the normalized effectiveness factor (NEF_(fluid))equation is unitless, it provides a convenient means of comparison ofvalues from different sources.

Use of the Mouromtseff equation approach to fluid evaluation impliesthat the local heat transfer process is the dominant mechanism whichdictates the fluids heat transfer performance. This is not always thecase. Fluid evaluation needs to be made based on an understanding of thedominant mechanism which dictates heat transfer performance. Thenormalized effectiveness factor (NEF_(fluid)) equation approach providesdifferent options for different applications. This provides a morerigorous and correct method for fluid evaluation.

In an embodiment, performance of a heat transfer system during operationis improved using a heat transfer fluid having a normalizedeffectiveness factor (NEF_(fluid)) value equal to or greater than 1.0,or greater than 1.1, or greater than 1.2, or greater than 1.3, orgreater than 1.4, or greater than 1.5, as compared to performance of aheat transfer system during operation using a heat transfer fluid havinga normalized effectiveness factor (NEF_(fluid)) value of less than 1.0.

The heat transfer fluids of this disclosure possess properties (e.g.,density (ρ), specific heat (c_(p)), and dynamic viscosity (μ)properties) for imparting satisfactory heat transfer performance inspecific devices. In addition, the heat transfer fluids of thisdisclosure can possess other properties that are beneficial for theiruse in specific devices. Such other properties include, for example,thermal conductivity (k) and flash point. In the heat transfer fluids ofthis disclosure, thermal conductivity (k) is not a significantcontributor to the normalized effectiveness factor (NEF_(fluid)),nevertheless having a fluid with a higher thermal conductivity (k) canbe a benefit because it increases the rate of heat transfer. Also, inthe heat transfer fluids of this disclosure, flash point is not asignificant contributor to the normalized effectiveness factor(NEF_(fluid)), nevertheless having a fluid with a higher flash point canbe a benefit because it reduces flammability. Further, heat transferfluids having properties that impart electrical compatibility, andcompatibility with materials in specific devices, can be beneficial inspecific devices.

As used herein, density (ρ) is determined in accordance with ASTM D8085or D4052, specific heat (c_(p)) is determined by ASTM E1269, and dynamicviscosity (μ) is determined by ASTM D8085 or derived from ASTM D445 andASTM D4052.

In an embodiment, at a temperature of 40° C., the heat transfer fluidsof this disclosure have a density (ρ) from about 0.25 g/mL to about 1.75g/mL, or from about 0.30 g/mL to about 1.70 g/mL, or from about 0.35g/mL to about 1.65 g/mL, or from about 0.40 g/mL to about 1.60 g/mL, orfrom about 0.45 g/mL to about 1.55 g/mL.

In another embodiment, at a temperature of 80° C., the heat transferfluids of this disclosure have a density (ρ) from about 0.25 g/mL toabout 1.75 g/mL, or from about 0.30 g/mL to about 1.70 g/mL, or fromabout 0.35 g/mL to about 1.65 g/mL, or from about 0.40 g/mL to about1.60 g/mL, or from about 0.45 g/mL to about 1.55 g/mL.

In an embodiment, at a temperature of 40° C., the heat transfer fluidsof this disclosure have a specific heat (c_(p)) from about 1.25 kJ/kg·Kto about 3.50 kJ/kg·K, or from about 1.35 kJ/kg·K to about 3.40 kJ/kg·K,or from about 1.45 kJ/kg·K to about 3.25 kJ/kg·K, or from about 1.50kJ/kg·K to about 3.20 kJ/kg·K, or from about 1.55 kJ/kg·K to about 3.15kJ/kg·K.

In another embodiment, at a temperature of 80° C., the heat transferfluids of this disclosure have a specific heat (c_(p)) from about 1.25kJ/kg·K to about 3.50 kJ/kg·K, or from about 1.35 kJ/kg·K to about 3.40kJ/kg·K, or from about 1.45 kJ/kg·K to about 3.25 kJ/kg·K, or from about1.50 kJ/kg·K to about 3.20 kJ/kg·K, or from about 1.55 kJ/kg·K to about3.15 kJ/kg·K.

In an embodiment, where the average fluid temperature is 40° C., theheat transfer fluids of this disclosure have a dynamic viscosity (μ)from about 0.50 centipoise (cP) to about 7.50 cP, or from about 0.55 cPto about 7.00 cP, or from about 0.65 cP to about 6.50 cP, or from about0.70 cP to about 6.00 cP, or from about 0.75 cP to about 5.50 cP.

In another embodiment, where the average fluid temperature is 80° C.,the heat transfer fluids of this disclosure have a dynamic viscosity (μ)from about 0.50 cP to about 7.50 cP, or from about 0.55 cP to about 7.00cP, or from about 0.65 cP to about 6.50 cP, or from about 0.70 cP toabout 6.00 cP, or from about 0.75 cP to about 5.50 cP.

In accordance with this disclosure, when heat conveyance is the dominantmode controlling performance of the heat transfer fluid in anapplication, the dimensional effectiveness factor (DEF_(fluid)) equationdependencies on fluid properties for the specified fluid circulationflow regimes and pump types are as follows:

1) for positive displacement pump and laminar heat transfer circuitdominant flow regime, both the DEF_(fluid) and the DEF_(reference) areρ¹ c_(p) ¹ μ⁻¹;

2) for positive displacement pump and transition heat transfer circuitdominant flow regime, both the DEF_(fluid) and the DEF_(reference) areρ^(0.25) c_(p) ¹ μ^(−0.25);

3) for centrifugal pump and laminar heat transfer circuit dominant flowregime, both the DEF_(fluid) and the DEF_(reference) are ρ^(0.19) c_(p)¹ μ^(−0.19); and

4) for centrifugal pump and transition heat transfer circuit dominantflow regime, both the DEF_(fluid) and the DEF_(reference) are ρ^(0.04)c_(p) ¹ μ^(−0.04).

Further, in accordance with this disclosure, when heat conveyance is thedominant mode controlling performance of the heat transfer fluid in anapplication, the dimensional effectiveness factor (DEF_(fluid)) equationdependencies on fluid properties for the specified fluid circulationflow regimes and pump types are as follows:

1) for positive displacement pump and laminar heat transfer circuitdominant flow regime, both the DEF_(fluid) and the DEF_(reference) areρ^(0.5-1.5) c_(p) ^(0.5-1.5) μ^(−1.5-0.5);

2) for positive displacement pump and transition heat transfer circuitdominant flow regime, both the DEF_(fluid) and the DEF_(reference) areρ^(0.1-0.5) c_(p) ^(0.5-1.5) μ^(−0.5-0.1);

3) for centrifugal pump and laminar heat transfer circuit dominant flowregime, both the DEF_(fluid) and the DEF_(reference) are ρ^(0.05-0.5)c_(p) ^(0.5-1.5) μ^(−105-0.05); and

4) for centrifugal pump and transition heat transfer circuit dominantflow regime, both the DEF_(fluid) and the DEF_(reference) areρ^(0.01-0.1) c_(p) ^(0.5-1.5) μ^(−0.1-0.01).

As described herein, improvement in performance of a heat transfersystem is obtained by using a heat transfer fluid having a normalizedeffectiveness factor (NEF_(fluid)) equal to or greater than 1, orgreater than 1.1, or greater than 1.15, or greater than 1.2, or greaterthan 1.25, or greater than 1.3, or greater than 1.35, or greater than1.4, or greater than 1.45, or greater than 1.5.

Illustrative reference fluids useful in this disclosure include, forexample, conventional fluids known in the art such as biphenyl26.5%+diphenyl oxide 73.5% (Dowtherm A), siloxane (>95%, KV100 16.6 cSt)(Duratherm S), organosilicate ester (>90%, KV100 0.93 cSt) (Coolanol20), organosilicate ester (>90%, KV100 1.6 cSt) (Coolanol 25R),perfluoro fluid C5-C8 (KV25 2.2 cSt) (Fluorinert FC-40),3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethyl-hexane(>99%) (Novec 7500), and the like.

The heat transfer fluids of this disclosure provide sustained heattransfer fluid properties over the lifetime of the heat transfer fluid,and compatibility with apparatus, e.g., electric vehicle, components andmaterials. Illustrative electric vehicle components that can be cooledin accordance with this disclosure include, for example, electricvehicle batteries, electric motors, electric generators,AC-DC/DC-AC/AC-AC/DC-DC converters, AC-DC/DC-AC/AC-AC/DC-DCtransformers, power management systems, electronics controllingbatteries, on-board chargers, on-board power electronics, super fastcharging systems, fast charging equipment at charging stations,stationary super fast chargers, and the like.

Depending on the particular apparatus (e.g., electric vehicle batteries,electric motors, electric generators, AC-DC/DC-AC/AC-AC/DC-DCconverters, AC-DC/DC-AC/AC-AC/DC-DC transformers, power managementsystems, electronics controlling batteries, on-board chargers, on-boardpower electronics, super fast charging systems, fast charging equipmentat charging stations, stationary super fast chargers, and the like), theapparatus can operate over a wide temperature range. For example, theapparatus can operate at a temperature between about −40° C. and about175° C., or between about −25° C. and about 170° C., or between about−10° C. and about 165° C., or between about 0° C. and about 160° C., orbetween about 10° C. and about 155° C., or between about 25° C. andabout 150° C., or between about 25° C. and about 125° C., or betweenabout 30° C. and about 120° C., or between about 35° C. and about 115°C., or between about 35° C. and about 105° C., or between about 35° C.and about 95° C., or between about 35° C. and about 85° C.

In an embodiment, a single heat transfer fluid can be used in theapparatus. In another embodiment, more than one heat transfer fluids canbe used in the apparatus, for example, one heat transfer fluid for thebattery and another heat transfer fluid for another component of theapparatus.

Further, the heat transfer fluids of this disclosure provide advantagedperformance on surfaces of apparatus components that include, forexample, the following: metals, metal alloys, non-metals, non-metalalloys, mixed carbon-metal composites and alloys, mixed carbon-nonmetalcomposites and alloys, ferrous metals, ferrous composites and alloys,non-ferrous metals, non-ferrous composites and alloys, titanium,titanium composites and alloys, aluminum, aluminum composites andalloys, magnesium, magnesium composites and alloys, ion-implanted metalsand alloys, plasma modified surfaces; surface modified materials;coatings; mono-layer, multi-layer, and gradient layered coatings; honedsurfaces; polished surfaces; etched surfaces; textured surfaces; microand nano structures on textured surfaces; super-finished surfaces;diamond-like carbon (DLC), DLC with high-hydrogen content, DLC withmoderate hydrogen content, DLC with low-hydrogen content, DLC withnear-zero hydrogen content, DLC composites, DLC-metal compositions andcomposites, DLC-nonmetal compositions and composites; ceramics, ceramicoxides, ceramic nitrides, FeN, CrN, ceramic carbides, mixed ceramiccompositions, and the like; polymers, thermoplastic polymers, engineeredpolymers, polymer blends, polymer alloys, polymer composites; materialscompositions and composites, that include, for example, graphite,carbon, molybdenum, molybdenum disulfide, polytetrafluoroethylene,polyperfluoropropylene, polyperfluoroalkylethers, and the like.

As used herein, the apparatus is not narrowly critical and can include,for example, an electric vehicle, a computer server farm, a chargingstation, a rechargeable battery system, and the like.

Over the years, researchers have developed many pressure dropcorrelations. As an example, one of the most widely utilizedcorrelations for calculating the pressure drop due to laminar flow in apipe is the Hagen-Poiseuille equation is commonly used for. The specificcorrelation to use will be dependent on the geometry and flow regimewhere the majority of pressure drop through the circuit occurs. For thisdisclosure, use was made of correlations for the “Fanning frictionfactor”, f, which is defined as:

${f = {\frac{1}{4}{\,^{{^\circ}}d}\frac{\Delta\; P}{L}\frac{1}{\frac{1}{2}\rho\; v^{2}}}},$where:

f—Fanning friction factor,

d—tube/pipe diameter,

ΔP—pressure drop,

L—equivalent length of tube/pipe,

ρ—average fluid density, and

v—fluid velocity.

Correlations for the friction factor have been developed as a functionof the Reynolds number as:

$\left( {{Re} = \frac{d\; v\;\rho}{µ}} \right).$

Laminar flow is defined as when the Re<2,100. In this flow regime, thefriction factor, f, is given by:

$f = {\frac{16}{Re}.}$

Transitional flow is defined as when the Re>2,100 and its frictionfactor can be described by the Blasius equation, listed below:

$f = {\frac{0.0791}{{Re}^{0.25}}.}$

Transition to fully turbulent flow depends on the roughness of the pipe.For smooth pipes, the Blasius equation above can be valid up to aReynolds number of 10⁷. For specific applications, reference can be madeto charts in references like R. B. Bird, W. E. Stewart and E. N.Lightfoot, “Transport Phenomena”, John Wiley & Sons, New York, 1960,where based on the roughness of the specific application, deviation fromthe Blasius equation can be determined.

While these specific correlations have been used to derive the exponentson the properties in the factors for this disclosure, it should be notedthat any specific pressure drop correlation could be used for anyspecific application. Equally, this approach could be used for any otherapplication, like for example, flow over the outside of a tube bank, or,axial flow through concentric rotating cylinders, like for instancewhich may be encountered when directly cooling a rotor/stator.

Heat Transfer Fluid Base Stocks and Cobase Stocks

A wide range of heat transfer fluid base oils is known in the art. Heattransfer fluid base oils that are useful in the present disclosure arenatural oils, mineral oils and synthetic oils, and unconventional oils(or mixtures thereof) can be used unrefined, refined, or rerefined (thelatter is also known as reclaimed or reprocessed oil). Unrefined oilsare those obtained directly from a natural or synthetic source and usedwithout added purification. These include shale oil obtained directlyfrom retorting operations, petroleum oil obtained directly from primarydistillation, and ester oil obtained directly from an esterificationprocess. Refined oils are similar to the oils discussed for unrefinedoils except refined oils are subjected to one or more purification stepsto improve at least one heat transfer fluid base oil property. Oneskilled in the art is familiar with many purification processes. Theseprocesses include solvent extraction, secondary distillation, acidextraction, base extraction, filtration, and percolation. Rerefined oilsare obtained by processes analogous to refined oils but using an oilthat has been previously used as a feed stock.

Groups I, II, III, IV and V are broad base oil stock categoriesdeveloped and defined by the American Petroleum Institute (APIPublication 1509; www.API.org) to create guidelines for heat transferfluid base oils. Group I base stocks have a viscosity index of betweenabout 80 to 120 and contain greater than about 0.03% sulfur and/or lessthan about 90% saturates. Group II base stocks have a viscosity index ofbetween about 80 to 120, and contain less than or equal to about 0.03%sulfur and greater than or equal to about 90% saturates. Group IIIstocks have a viscosity index greater than about 120 and contain lessthan or equal to about 0.03% sulfur and greater than about 90%saturates. Group IV includes polyalphaolefins (PAO). Group V base stockincludes base stocks not included in Groups I-IV. The Table 2 belowsummarizes properties of each of these five groups.

TABLE 2 Base Oil Properties Saturates Sulfur Viscosity Index Group I <90and/or >0.03% and ≥80 and <120 Group II ≥90 and ≤0.03% and ≥80 and <120Group III ≥90 and ≤0.03% and ≥120 Group IV polyalphaolefins (PAO) GroupV All other base oil stocks not included in Groups I, II, III or IV

Natural oils include animal oils, vegetable oils (castor oil and lardoil, for example), and mineral oils. Animal and vegetable oilspossessing favorable thermal oxidative stability can be used. Of thenatural oils, mineral oils are preferred. Mineral oils vary widely as totheir crude source, for example, as to whether they are paraffinic,naphthenic, or mixed paraffinic-naphthenic. Oils derived from coal orshale are also useful. Natural oils vary also as to the method used fortheir production and purification, for example, their distillation rangeand whether they are straight run or cracked, hydrorefined, or solventextracted.

Group II and/or Group III hydroprocessed or hydrocracked base stocks,including synthetic oils such as alkyl aromatics and synthetic estersare also well known base stock oils.

Synthetic oils include hydrocarbon oil. Hydrocarbon oils include oilssuch as polymerized and interpolymerized olefins (polybutylenes,polypropylenes, propylene isobutylene copolymers, ethylene-olefincopolymers, and ethylene-alphaolefin copolymers, for example).Polyalphaolefin (PAO) oil base stocks are commonly used synthetichydrocarbon oil. By way of example, PAOs derived from C₈, C₁₀, C₁₂, C₁₄olefins or mixtures thereof may be utilized. See U.S. Pat. Nos.4,956,122; 4,827,064; and 4,827,073.

The number average molecular weights of the PAOs, which are knownmaterials and to generally available on a major commercial scale fromsuppliers such as ExxonMobil Chemical Company, Chevron Phillips ChemicalCompany, BP, and others, typically vary from about 250 to about 3,000,although PAO's may be made in viscosities up to about 350 cSt (100° C.).The PAOs are typically comprised of relatively low molecular weighthydrogenated polymers or oligomers of alphaolefins which include, butare not limited to, C₂ to about C₃₂ alphaolefins with the C₈ to aboutC₁₆ alphaolefins, such as 1-octene, 1-decene, 1-dodecene and the like,being preferred. The preferred polyalphaolefins are poly-1-octene,poly-1-decene and poly-1-dodecene and mixtures thereof and mixedolefin-derived polyolefins. However, the dimers of higher olefins in therange of C₁₄ to C₁₈ may be used to provide low viscosity base stocks ofacceptably low volatility. Depending on the viscosity grade and thestarting oligomer, the PAOs may be predominantly trimers and tetramersof the starting olefins, with minor amounts of the higher oligomers,having a viscosity range of 1.5 to 12 cSt. PAO fluids of particular usemay include 3.0 cSt, 3.4 cSt, and/or 3.6 cSt and combinations thereof.Mixtures of PAO fluids having a viscosity range of 1.5 to approximately350 cSt or more may be used if desired.

The PAO fluids may be conveniently made by the polymerization of analphaolefin in the presence of a polymerization catalyst such as theFriedel-Crafts catalysts including, for example, aluminum trichloride,boron trifluoride or complexes of boron trifluoride with water, alcoholssuch as ethanol, propanol or butanol, carboxylic acids or esters such asethyl acetate or ethyl propionate. For example the methods disclosed byU.S. Pat. No. 4,149,178 or 3,382,291 may be conveniently used herein.Other descriptions of PAO synthesis are found in the following U.S. Pat.Nos. 3,742,082; 3,769,363; 3,876,720; 4,239,930; 4,367,352; 4,413,156;4,434,408; 4,910,355; 4,956,122; and 5,068,487. The dimers of the C₁₄ toC₁₈ olefins are described in U.S. Pat. No. 4,218,330.

Other useful heat transfer fluid oil base stocks include wax isomeratebase stocks and base oils, comprising hydroisomerized waxy stocks (e.g.waxy stocks such as gas oils, slack waxes, fuels hydrocracker bottoms,etc.), hydroisomerized Fischer-Tropsch waxes, Gas-to-Liquids (GTL) basestocks and base oils, and other wax isomerate hydroisomerized basestocks and base oils, or mixtures thereof. Fischer-Tropsch waxes, thehigh boiling point residues of Fischer-Tropsch synthesis, are highlyparaffinic hydrocarbons with very low sulfur content. Thehydroprocessing used for the production of such base stocks may use anamorphous hydrocracking/hydroisomerization catalyst, such as one of thespecialized lube hydrocracking (LHDC) catalysts or a crystallinehydrocracking/hydroisomerization catalyst, preferably a zeoliticcatalyst. For example, one useful catalyst is ZSM-48 as described inU.S. Pat. No. 5,075,269, the disclosure of which is incorporated hereinby reference in its entirety. Processes for makinghydrocracked/hydroisomerized distillates andhydrocracked/hydroisomerized waxes are described, for example, in U.S.Pat. Nos. 2,817,693; 4,975,177; 4,921,594 and 4,897,178 as well as inBritish Patent Nos. 1,429,494; 1,350,257; 1,440,230 and 1,390,359. Eachof the aforementioned patents is incorporated herein in their entirety.Particularly favorable processes are described in European PatentApplication Nos. 464546 and 464547, also incorporated herein byreference. Processes using Fischer-Tropsch wax feeds are described inU.S. Pat. Nos. 4,594,172 and 4,943,672, the disclosures of which areincorporated herein by reference in their entirety.

Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils,and other wax-derived hydroisomerized (wax isomerate) base oils beadvantageously used in the instant disclosure, and may have usefulkinematic viscosities at 100° C. of about 3 cSt to about 50 cSt,preferably about 3 cSt to about 30 cSt, more preferably about 3.5 cSt toabout 25 cSt, as exemplified by GTL 4 with kinematic viscosity of about4.0 cSt at 100° C. and a viscosity index of about 141. TheseGas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base oils,and other wax-derived hydroisomerized base oils may have useful pourpoints of about −20° C. or lower, and under some conditions may haveadvantageous pour points of about −25° C. or lower, with useful pourpoints of about −30° C. to about −40° C. or lower. Useful compositionsof Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived baseoils, and wax-derived hydroisomerized base oils are recited in U.S. Pat.Nos. 6,080,301; 6,090,989, and 6,165,949 for example, and areincorporated herein in their entirety by reference.

The hydrocarbyl aromatics can be used as a base oil or base oilcomponent and can be any hydrocarbyl molecule that contains at leastabout 5% of its weight derived from an aromatic moiety such as abenzenoid moiety or naphthenoid moiety, or their derivatives. Thesehydrocarbyl aromatics include alkyl benzenes, alkyl naphthalenes, alkyldiphenyl oxides, alkyl naphthols, alkyl diphenyl sulfides, alkylatedbis-phenol A, alkylated thiodiphenol, and the like. The aromatic can bemono-alkylated, dialkylated, polyalkylated, and the like. The aromaticcan be mono- or poly-functionalized. The hydrocarbyl groups can also becomprised of mixtures of alkyl groups, alkenyl groups, alkynyl,cycloalkyl groups, cycloalkenyl groups and other related hydrocarbylgroups. The hydrocarbyl groups can range from about C₆ up to about C₆₀with a range of about C₈ to about C₂₀ often being preferred. A mixtureof hydrocarbyl groups is often preferred, and up to about three suchsubstituents may be present. The hydrocarbyl group can optionallycontain sulfur, oxygen, and/or nitrogen containing substituents. Thearomatic group can also be derived from natural (petroleum) sources,provided at least about 5% of the molecule is comprised of an above-typearomatic moiety. Viscosities at 100° C. of approximately 3 cSt to about50 cSt are preferred, with viscosities of approximately 3.4 cSt to about20 cSt often being more preferred for the hydrocarbyl aromaticcomponent. In one embodiment, an alkyl naphthalene where the alkyl groupis primarily comprised of 1-hexadecene is used. Other alkylates ofaromatics can be advantageously used. Naphthalene or methyl naphthalene,for example, can be alkylated with olefins such as octene, decene,dodecene, tetradecene or higher, mixtures of similar olefins, and thelike. Useful concentrations of hydrocarbyl aromatic in a heat transferfluid composition can be about 2% to about 25%, preferably about 4% toabout 20%, and more preferably about 4% to about 15%, depending on theapplication.

Alkylated aromatics such as the hydrocarbyl aromatics of the presentdisclosure may be produced by well-known Friedel-Crafts alkylation ofaromatic compounds. See Friedel-Crafts and Related Reactions, Olah, G.A. (ed.), Inter-science Publishers, New York, 1963. For example, anaromatic compound, such as benzene or naphthalene, is alkylated by anolefin, alkyl halide or alcohol in the presence of a Friedel-Craftscatalyst. See Friedel-Crafts and Related Reactions, Vol. 2, part 1,chapters 14, 17, and 18, See Olah, G. A. (ed.), Inter-sciencePublishers, New York, 1964. Many homogeneous or heterogeneous, solidcatalysts are known to one skilled in the art. The choice of catalystdepends on the reactivity of the starting materials and product qualityrequirements. For example, strong acids such as AlCl₃, BF₃, or HF may beused. In some cases, milder catalysts such as FeCl₃ or SnCl₄ arepreferred. Newer alkylation technology uses zeolites or solid superacids.

Esters comprise a useful base stock. Additive solvency and sealcompatibility characteristics may be secured by the use of esters suchas the esters of dibasic acids with monoalkanols and the polyol estersof monocarboxylic acids. Esters of the former type include, for example,the esters of dicarboxylic acids such as phthalic acid, succinic acid,alkyl succinic acid, alkenyl succinic acid, maleic acid, azelaic acid,suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic aciddimer, malonic acid, alkyl malonic acid, alkenyl malonic acid, etc.,with a variety of alcohols such as butyl alcohol, hexyl alcohol, dodecylalcohol, 2-ethylhexyl alcohol, etc. Specific examples of these types ofesters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexylfumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate,dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, etc.

Particularly useful synthetic esters are those which are obtained byreacting one or more polyhydric alcohols, preferably the hinderedpolyols (such as the neopentyl polyols, e.g., neopentyl glycol,trimethylol ethane, 2-methyl-2-propyl-1,3-propanediol, trimethylolpropane, pentaerythritol and dipentaerythritol) with alkanoic acidscontaining at least about 4 carbon atoms, preferably C₅ to C₃₀ acidssuch as saturated straight chain fatty acids including caprylic acid,capric acid, lauric acid, myristic acid, palmitic acid, stearic acid,arachic acid, and behenic acid, or the corresponding branched chainfatty acids or unsaturated fatty acids such as oleic acid, or mixturesof any of these materials.

Suitable synthetic ester components include the esters of trimethylolpropane, trimethylol butane, trimethylol ethane, pentaerythritol and/ordipentaerythritol with one or more monocarboxylic acids containing fromabout 5 to about 10 carbon atoms. These esters are widely availablecommercially, for example, the Mobil P-41 and P-51 esters of ExxonMobilChemical Company.

Also useful are esters derived from renewable material such as coconut,palm, rapeseed, soy, sunflower and the like. These esters may bemonoesters, di-esters, polyol esters, complex esters, or mixturesthereof. These esters are widely available commercially, for example,the Mobil P-51 ester of ExxonMobil Chemical Company.

Heat transfer fluid formulations containing renewable esters areincluded in this disclosure. For such formulations, the renewablecontent of the ester is typically greater than about 70 weight percent,preferably more than about 80 weight percent and most preferably morethan about 90 weight percent.

Other useful fluids include non-conventional or unconventional basestocks that have been processed, preferably catalytically, orsynthesized to provide high performance heat transfer characteristics.

Non-conventional or unconventional base stocks/base oils include one ormore of a mixture of base stock(s) derived from one or moreGas-to-Liquids (GTL) materials, as well as isomerate/isodewaxate basestock(s) derived from natural wax or waxy feeds, mineral and ornon-mineral oil waxy feed stocks such as slack waxes, natural waxes, andwaxy stocks such as gas oils, waxy fuels hydrocracker bottoms, waxyraffinate, hydrocrackate, thermal crackates, or other mineral, mineraloil, or even non-petroleum oil derived waxy materials such as waxymaterials received from coal liquefaction or shale oil, and mixtures ofsuch base stocks.

GTL materials are materials that are derived via one or more synthesis,combination, transformation, rearrangement, and/ordegradation/deconstructive processes from gaseous carbon-containingcompounds, hydrogen-containing compounds and/or elements as feed stockssuch as hydrogen, carbon dioxide, carbon monoxide, water, methane,ethane, ethylene, acetylene, propane, propylene, propyne, butane,butylenes, and butynes. GTL base stocks and/or base oils are GTLmaterials that are generally derived from hydrocarbons; for example,waxy synthesized hydrocarbons, that are themselves derived from simplergaseous carbon-containing compounds, hydrogen-containing compoundsand/or elements as feed stocks. GTL base stock(s) and/or base oil(s)include oils boiling in the lube oil boiling range (1)separated/fractionated from synthesized GTL materials such as, forexample, by distillation and subsequently subjected to a final waxprocessing step which involves either or both of a catalytic dewaxingprocess, or a solvent dewaxing process, to produce lube oils ofreduced/low pour point; (2) synthesized wax isomerates, comprising, forexample, hydrodewaxed or hydroisomerized cat and/or solvent dewaxedsynthesized wax or waxy hydrocarbons; (3) hydrodewaxed orhydroisomerized cat and/or solvent dewaxed Fischer-Tropsch (F-T)material (i.e., hydrocarbons, waxy hydrocarbons, waxes and possibleanalogous oxygenates); preferably hydrodewaxed orhydroisomerized/followed by cat and/or solvent dewaxing dewaxed F-T waxyhydrocarbons, or hydrodewaxed or hydroisomerized/followed by cat (orsolvent) dewaxing dewaxed, F-T waxes, or mixtures thereof.

GTL base stock(s) and/or base oil(s) derived from GTL materials,especially, hydrodewaxed or hydroisomerized/followed by cat and/orsolvent dewaxed wax or waxy feed, preferably F-T material derived basestock(s) and/or base oil(s), are characterized typically as havingkinematic viscosities at 100° C. of from about 2 mm²/s to about 50 mm²/s(ASTM D445). They are further characterized typically as having pourpoints of −5° C. to about −40° C. or lower (ASTM D97). They are alsocharacterized typically as having viscosity indices of about 80 to about140 or greater (ASTM D2270).

In addition, the GTL base stock(s) and/or base oil(s) are typicallyhighly paraffinic (>90% saturates), and may contain mixtures ofmonocycloparaffins and multicycloparaffins in combination withnon-cyclic isoparaffins. The ratio of the naphthenic (i.e.,cycloparaffin) content in such combinations varies with the catalyst andtemperature used. Further, GTL base stock(s) and/or base oil(s)typically have very low sulfur and nitrogen content, generallycontaining less than about 10 ppm, and more typically less than about 5ppm of each of these elements. The sulfur and nitrogen content of GTLbase stock(s) and/or base oil(s) obtained from F-T material, especiallyF-T wax, is essentially nil. In addition, the absence of phosphorous andaromatics make this materially especially suitable for the formulationof low SAP products.

The term GTL base stock and/or base oil and/or wax isomerate base stockand/or base oil is to be understood as embracing individual fractions ofsuch materials of wide viscosity range as recovered in the productionprocess, mixtures of two or more of such fractions, as well as mixturesof one or two or more low viscosity fractions with one, two or morehigher viscosity fractions to produce a blend wherein the blend exhibitsa target kinematic viscosity.

The GTL material, from which the GTL base stock(s) and/or base oil(s)is/are derived is preferably an F-T material (i.e., hydrocarbons, waxyhydrocarbons, wax).

Base oils for use in the formulated heat transfer fluids useful in thepresent disclosure are any of the variety of oils corresponding to APIGroup I, Group II, Group III, Group IV, and Group V oils, and mixturesthereof, preferably API Group II, Group III, Group IV, and Group V oils,and mixtures thereof, more preferably Group III, Group IV, and Group Vbase oils, and mixtures thereof. Highly paraffinic base oils can be usedto advantage in the formulated heat transfer fluids useful in thepresent disclosure. Minor quantities of Group I stock, such as theamount used to dilute additives for blending into formulated lube oilproducts, can also be used. Even in regard to the Group II stocks, it ispreferred that the Group II stock be in the higher quality rangeassociated with that stock, i.e. a Group II stock having a viscosityindex in the range 100<VI<120.

Preferred base fluids for use in the formulated heat transfer fluidsuseful in the present disclosure include, for example, aromatichydrocarbons, polyolefins, paraffins, isoparaffins, esters, ethers,fluorinated fluids, nano fluids, and silicone oils.

The base oil constitutes the major component of the heat transfer fluidcomposition of the present disclosure and typically is present in anamount ranging from about 50 to about 99 weight percent, preferably fromabout 70 to about 95 weight percent, and more preferably from about 85to about 95 weight percent, based on the total weight of thecomposition. The base oil conveniently has a kinematic viscosity,according to ASTM standards, of about 2.5 cSt to about 12 cSt (or mm²/s)at 100° C. and preferably of about 2.5 cSt to about 9 cSt (or mm²/s) at100° C. Mixtures of synthetic and natural base oils may be used ifdesired. Bi-modal mixtures of Group I, II, III, IV, and/or V base stocksmay be used if desired.

Heat Transfer Fluid Additives

The formulated heat transfer fluid useful in the present disclosure mayadditionally contain one or more commonly used heat transfer fluidperformance additives including but not limited to antioxidants,corrosion inhibitors, antifoam agents, nanomaterials, nanoparticles, andothers. These additives are commonly delivered with varying amounts ofdiluent oil, that may range from 5 weight percent to 50 weight percent.

The additives useful in this disclosure do not have to be soluble in theheat transfer fluids.

The types and quantities of performance additives used in combinationwith the instant disclosure in heat transfer fluid compositions are notlimited by the examples shown herein as illustrations.

Antioxidants

The heat transfer fluids typically include at least one antioxidant.Antioxidants retard the oxidative degradation of base oils duringservice. Such degradation may result in deposits on metal surfaces, thepresence of sludge, or a viscosity increase in the heat transfer fluid.One skilled in the art knows a wide variety of oxidation inhibitors thatare useful in heat transfer fluids. See, Klamann in Lubricants andRelated Products, op cite, and U.S. Pat. Nos. 4,798,684 and 5,084,197,for example.

Illustrative antioxidants include sterically hindered alkyl phenols suchas 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol and2,6-di-tert-butyl-4-(2-octyl-3-propanoic) phenol; N,N-di(alkylphenyl)amines; and alkylated phenylenediamines.

The antioxidant may be a hindered phenolic antioxidant such as butylatedhydroxytoluene, suitably present in an amount of 0.01 to 5%, preferably0.4 to 0.8%, by weight of the heat transfer fluid. Alternatively, or inaddition, the antioxidant may comprise an aromatic amine antioxidantsuch as mono-octylphenylalphanapthyl amine or p,p-dioctyldiphenylamine,used singly or in admixture. The amine antioxidant component is suitablypresent in a range of from 0.01 to 5% by weight of the heat transferfluid, more preferably 0.5 to 1.5%.

Useful antioxidants include hindered phenols. These phenolicantioxidants may be ashless (metal-free) phenolic compounds or neutralor basic metal salts of certain phenolic compounds. Typical phenolicantioxidant compounds are the hindered phenolics which are the oneswhich contain a sterically hindered hydroxyl group, and these includethose derivatives of dihydroxy aryl compounds in which the hydroxylgroups are in the o- or p-position to each other. Typical phenolicantioxidants include the hindered phenols substituted with C₆+alkylgroups and the alkylene coupled derivatives of these hindered phenols.Examples of phenolic materials of this type 2-t-butyl-4-heptyl phenol;2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecyl phenol;2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol;2-methyl-6-t-butyl-4-heptyl phenol; and 2-methyl-6-t-butyl-4-dodecylphenol. Other useful hindered mono-phenolic antioxidants may include forexample hindered 2,6-di-alkyl-phenolic proprionic ester derivatives.Bis-phenolic antioxidants may also be advantageously used in combinationwith the instant disclosure. Examples of ortho-coupled phenols include:2,2′-bis(4-heptyl-6-t-butyl-phenol); 2,2′-bis(4-octyl-6-t-butyl-phenol);and 2,2′-bis(4-dodecyl-6-t-butyl-phenol). Para-coupled bisphenolsinclude for example 4,4′-bis(2,6-di-t-butyl phenol) and4,4′-methylene-bis(2,6-di-t-butyl phenol).

Other illustrative phenolic antioxidants include sulfurized andnon-sulfurized phenolic antioxidants. The terms “phenolic type” or“phenolic antioxidant” used herein includes compounds having one or morethan one hydroxyl group bound to an aromatic ring which may itself bemononuclear, e.g., benzyl, or poly-nuclear, e.g., naphthyl and Spiroaromatic compounds. Thus “phenol type” includes phenol per se, catechol,resorcinol, hydroquinone, naphthol, etc., as well as alkyl or alkenyland sulfurized alkyl or alkenyl derivatives thereof, and bisphenol typecompounds including such bi-phenol compounds linked by alkylene bridgessulfuric bridges or oxygen bridges. Alkyl phenols include mono- andpoly-alkyl or alkenyl phenols, the alkyl or alkenyl group containingfrom 3-100 carbons, preferably 4 to 50 carbons and sulfurizedderivatives thereof, the number of alkyl or alkenyl groups present inthe aromatic ring ranging from 1 to up to the available unsatisfiedvalences of the aromatic ring remaining after counting the number ofhydroxyl groups bound to the aromatic ring.

Generally, therefore, the phenolic antioxidant may be represented by thegeneral formula:(R)_(x)—Ar—(OH)_(y)where Ar is selected from the group consisting of:

wherein R is a C₃-C₁₀₀ alkyl or alkenyl group, a sulfur substitutedalkyl or alkenyl group, preferably a C₄-C₅₀ alkyl or alkenyl group orsulfur substituted alkyl or alkenyl group, more preferably C₃-C₁₀₀ alkylor sulfur substituted alkyl group, most preferably a C₄-C₅₀ alkyl group,R^(g) is a C₁-C₁₀₀ alkylene or sulfur substituted alkylene group,preferably a C₂-C₂₀ alkylene or sulfur substituted alkylene group, morepreferably a C₂-C₂₀ alkylene or sulfur substituted alkylene group, y isat least 1 to up to the available valences of Ar, x ranges from 0 to upto the available valances of Ar-y, z ranges from 1 to 10, n ranges from0 to 20, and m is 0 to 4 and p is 0 or 1, preferably y ranges from 1 to3, x ranges from 0 to 3, z ranges from 1 to 4 and n ranges from 0 to 5,and p is 0.

Preferred phenolic antioxidant compounds are the hindered phenolics andphenolic esters which contain a sterically hindered hydroxyl group, andthese include those derivatives of dihydroxy aryl compounds in which thehydroxyl groups are in the o- or p-position to each other. Typicalphenolic antioxidants include the hindered phenols substituted withC.sub.1+alkyl groups and the alkylene coupled derivatives of thesehindered phenols. Examples of phenolic materials of this type2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecylphenol; 2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol;2-methyl-6-t-butyl-4-heptyl phenol; 2-methyl-6-t-butyl-4-dodecyl phenol;2,6-di-t-butyl-4 methyl phenol; 2,6-di-t-butyl-4-ethyl phenol; and2,6-di-t-butyl 4 alkoxy phenol; and

Phenolic type antioxidants are well known in the heat transfer fluidindustry and commercial examples such as Ethanox™ 1710, Irganox™ 1076,Irganox™ L1035, Irganox™ 1010, Irganox™ L109, Irganox™ L118, Irganox™L135 and the like are familiar to those skilled in the art. The above ispresented only by way of exemplification, not limitation on the type ofphenolic antioxidants which can be used.

Other examples of phenol-based antioxidants include 2-t-butylphenol,2-t-butyl-4-methylphenol, 2-t-butyl-5-methylphenol,2,4-di-t-butylphenol, 2,4-dimethyl-6-t-butylphenol,2-t-butyl-4-methoxyphenol, 3-t-butyl-4-methoxyphenol,2,5-di-t-butylhydroquinone (manufactured by the Kawaguchi Kagaku Co.under trade designation “Antage DBH”), 2,6-di-t-butylphenol and2,6-di-t-butyl-4-alkylphenols such as 2,6-di-t-butyl-4-methylphenol and2,6-di-t-butyl-4-ethylphenol; 2,6-di-t-butyl-4-alkoxyphenols such as2,6-di-t-butyl-4-methoxyphenol and 2,6-di-t-butyl-4-ethoxy phenol,3,5-di-t-butyl-4-hydroxybenzylmercaptoocty-1 acetate,alkyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionates such asn-octyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (manufactured bythe Yoshitomi Seiyaku Co. under the trade designation “Yonox SS”),n-dodecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate and2′-ethylhexyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate;2,6-di-t-butyl-alpha-dimethylamino-p-cresol,2,2′-methylenebis(4-alkyl-6-t-butylphenol) compounds such as2,2′-methylenebis(4-methyl-6-t-butylphe-nol) (manufactured by theKawaguchi Kagaku Co. under the trade designation “Antage W-400”) and2,2′-methylenebis(4-ethyl-6-t-butylphenol) (manufactured by theKawaguchi Kagaku Co. under the trade designation “Antage W-500”);bisphenols such as 4,4′-butylidenebis(3-methyl-6-t-butyl-phenol)(manufactured by the Kawaguchi Kagaku Co. under the trade designation“Antage W-300”), 4,4′-methylenebis(2,6-di-t-butylphenol) (manufacturedby Laporte Performance Chemicals under the trade designation “Ionox220AH”), 4,4′-bis(2,6-di-t-butylphenol), 2,2-(di-p-hydroxyphenyl)propane(Bisphenol A), 2,2-bis(3,5-di-t-butyl-4-hydroxyphenyl)propane,4,4′-cyclohexydenebis(2,6-di-t-butylphenol), hexamethylene glycol bis[3, (3,5-di-t-butyl-4-hydroxyphenyl)propionate] (manufactured by theCiba Specialty Chemicals Co. under the trade designation “IrganoxL109”), triethylene glycolbis[3-(3-t-butyl-4-hydroxy-y-5-methylphenyl)propionate] (manufactured bythe Yoshitomi Seiyaku Co. under the trade designation “Tominox 917”),2,2′-thio[diethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate](manufactured by the Ciba Speciality Chemicals Co. under the tradedesignation “Irganox L115”),3,9-bis{1,1-dimethyl-2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)-propionyloxy]ethyl}2,4,8,10-tetraoxaspiro[5,5]undecane(manufactured by the Sumitomo Kagaku Co. under the trade designation“Sumilizer GA80”) and 4,4′-thiobis(3-methyl-6-t-butylphenol)(manufactured by the Kawaguchi Kagaku Co. under the trade designation“Antage RC”), 2,2′-thiobis(4,6-di-t-butylresorcinol); polyphenols suchas tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionato[methane(manufactured by the Ciba Speciality Chemicals Co. under the tradedesignation “Irganox L101”),1,1,3-tris(2-methyl-4-hydroxy-5-t-butylpheny-1)butane (manufactured bythe Yoshitomi Seiyaku Co. under the trade designation “Yoshinox 930”),1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene(manufactured by Ciba Speciality Chemicals under the trade designation“Irganox 330”), bis[3,3′-bis(4′-hydroxy-3′-t-butylpheny-1)butyric acid]glycol ester,2-(3′,5′-di-t-butyl-4-hydroxyphenyl)-methyl-4-(2″,4″-di-t-butyl-3″-hydroxyphenyl)methyl-6-t-butylphenoland 2,6-bis(2′-hydroxy-3′-t-butyl-5′-methylbenzyl)-4-methylphenol; andphenol/aldehyde condensates such as the condensates of p-t-butylphenoland formaldehyde and the condensates of p-t-butylphenol andacetaldehyde.

Effective amounts of one or more catalytic antioxidants may also beused. The catalytic antioxidants comprise an effective amount of a) oneor more oil soluble polymetal organic compounds; and, effective amountsof b) one or more substituted N,N′-diaryl-o-phenylenediamine compoundsor c) one or more hindered phenol compounds; or a combination of both b)and c). Catalytic antioxidants are more fully described in U.S. Pat. No.8,048,833, herein incorporated by reference in its entirety.

Illustrative aromatic amine antioxidants include phenyl-alpha-naphthylamine which is described by the following molecular structure:

wherein R^(z) is hydrogen or a C₁ to C₁₄ linear or C₃ to C₁₄ branchedalkyl group, preferably C₁ to C₁₀ linear or C₃ to C₁₀ branched alkylgroup, more preferably linear or branched C₆ to C₈ and n is an integerranging from 1 to 5 preferably 1. A particular example is Irganox L06.

Other aromatic amine antioxidants include other alkylated andnon-alkylated aromatic amines such as aromatic monoamines.

Typical aromatic amines antioxidants have alkyl substituent groups of atleast 6 carbon atoms. Examples of aliphatic groups include hexyl,heptyl, octyl, nonyl, and decyl. Generally, the aliphatic groups willnot contain more than 14 carbon atoms. The general types of such otheradditional amine antioxidants which may be present includediphenylamines, phenothiazines, imidodibenzyls and diphenyl phenylenediamines. Mixtures of two or more of such other additional aromaticamines may also be present. Polymeric amine antioxidants can also beused.

The antioxidants or oxidation inhibitors that are useful in heattransfer fluids of the disclosure are the hindered phenols (e.g.,2,6-di-(t-butyl)phenol); aromatic amines (e.g., alkylated diphenylamines); alkyl polysulfides; selenides; borates (e.g., epoxide/boricacid reaction products); phosphorodithioic acids, esters and/or salts;and the dithiocarbamate (e.g., zinc dithiocarbamates). In an embodiment,these antioxidants or oxidation inhibitors can be employed individuallyor at ratios of amine/phenolic from 1:10 to 10:1 of the mixturespreferred.

The antioxidants or oxidation inhibitors that are also useful in heattransfer fluid compositions of the disclosure are chlorinated aliphatichydrocarbons such as chlorinated wax; organic sulfides and polysulfidessuch as benzyl disulfide, bis(chlorobenzyl)disulfide, dibutyltetrasulfide, sulfurized methyl ester of oleic acid, sulfurizedalkylphenol, sulfurized dipentene, and sulfurized terpene;phosphosulfiirized hydrocarbons such as the reaction product of aphosphorus sulfide with turpentine or methyl oleate, phosphorus estersincluding principally dihydrocarbon and trihydrocarbon phosphites suchas dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite,pentylphenyl phosphite, dipentylphenyl phosphite, tridecyl phosphite,distearyl phosphite, dimethyl naphthyl phosphite, oleyl 4-pentylphenylphosphite, polypropylene (molecular weight 500)-substituted phenylphosphite, diisobutyl-substituted phenyl phosphite; metalthiocarbamates, such as zinc dioctyldithiocarbamate, and bariumheptylphenyl dithiocarbamate; Group II metal phosphorodithioates such aszinc dicyclohexylphosphorodithioate, zinc dioctylphosphorodithioate,barium di(heptylphenyl)(phosphorodithioate, cadmiumdinonylphosphorodithioate, and the reaction of phosphorus pentasulfidewith an equimolar mixture of isopropyl alcohol, 4-methyl-2-pentanol, andn-hexyl alcohol.

Oxidation inhibitors including organic compounds containing sulfur,nitrogen, phosphorus and some alkylphenols are useful additives in theheat transfer fluid formulations of this disclosure. Two general typesof oxidation inhibitors are those that react with the initiators, peroxyradicals, and hydroperoxides to form inactive compounds, and those thatdecompose these materials to form less active compounds. Examples arehindered (alkylated) phenols, e.g.6-di(tert-butyl)-4-methyl-phenol[2,6-di(tert-butyl)-p-cresol, DBPC], andaromatic amines, e.g. N-phenyl-alpha-naphthalamine.

Sulfurized alkyl phenols and alkali or alkaline earth metal saltsthereof also are useful antioxidants.

Another class of antioxidant used in heat transfer fluid compositionsand which may also be present are oil-soluble copper compounds. Anyoil-soluble suitable copper compound may be blended into the heattransfer fluid. Examples of suitable copper antioxidants include copperdihydrocarbyl thio- or dithio-phosphates and copper salts of carboxylicacid (naturally occurring or synthetic). Other suitable copper saltsinclude copper dithiacarbamates, sulphonates, phenates, andacetylacetonates. Basic, neutral, or acidic copper Cu(I) and or Cu(II)salts derived from alkenyl succinic acids or anhydrides are known to beparticularly useful.

A sulfur-containing antioxidant may be any and every antioxidantcontaining sulfur, for example, including dialkyl thiodipropionates suchas dilauryl thiodipropionate and distearyl thiodipropionate,dialkyldithiocarbamic acid derivatives (excluding metal salts),bis(3,5-di-t-butyl-4-hydroxybenzyl)sulfide, mercaptobenzothiazole,reaction products of phosphorus pentoxide and olefins, and dicetylsulfide. Of these, preferred are dialkyl thiodipropionates such asdilauryl thiodipropionate and distearyl thiodipropionate. The amine-typeantioxidant includes, for example, monoalkyldiphenylamines such asmonooctyldiphenylamine and monononyldiphenyl amine;dialkyldiphenylamines such as 4,4′-dibutyldiphenylamine,4,4′-dipentyldiphenylamine, 4,4′-dihexyldiphenylamine,4,4′-diheptyldiphenylamine, 4,4′-dioctyldiphenylamine and4,4′-dinonyldiphenylamine; polyalkyldiphenylamines such astetrabutyldiphenylamine, tetrahexyldiphenylamine,tetraoctyldiphenylamine and tetranonyldiphenylamine; and naphthylaminessuch as alpha-naphthylamine, phenyl-alpha-naphthylamine,butylphenyl-alpha-naphthylamine, pentylphenyl-alpha-naphthylamine,hexylphenyl-alpha-naphthylamine, heptylphenyl-alpha-naphthylamine,octylphenyl-alpha-naphthyl amine and nonylphenyl-alpha-naphthylamine. Ofthese, preferred are dialkyldiphenylamines.

Examples of sulphur-based antioxidants include dialkylsulphides such asdidodecylsulphide and dioctadecylsulphide; thiodipropionic acid esterssuch as didodecyl thiodipropionate, dioctadecyl thiodipropionate,dimyristyl thiodipropionate and dodecyloctadecyl thiodipropionate, and2-mercaptobenzimidazole.

Such antioxidants may be used individually or as mixtures of one or moretypes of antioxidants, the total amount employed being an amount ofabout 0.01 to about 5 wt %, preferably 0.1 to about 4.5 wt %, morepreferably 0.25 to 3 wt % (on an as-received basis).

Corrosion Inhibitors

The heat transfer fluid compositions can include at least one corrosioninhibitor. Corrosion inhibitors are used to reduce the degradation ofmetallic parts that are in contact with the heat transfer fluid oilcomposition. Suitable corrosion inhibitors include aryl thiazines, alkylsubstituted dimercaptothiodiazoles, alkyl substituteddimercaptothiadiazoles, and mixtures thereof.

Corrosion inhibitors are additives that protect metal surfaces againstchemical attack by water or other contaminants. A wide variety of theseare commercially available. As used herein, corrosion inhibitors includeantirust additives and metal deactivators.

One type of corrosion inhibitor is a polar compound that wets the metalsurface preferentially, protecting it with a film of oil. Another typeof corrosion inhibitor absorbs water by incorporating it in awater-in-oil emulsion so that only the oil touches the metal surface.Yet another type of corrosion inhibitor chemically adheres to the metalto produce a non-reactive surface. Examples of suitable additivesinclude zinc dithiophosphates, metal phenolates, basic metal sulfonates,fatty acids and amines. Such additives may be used in an amount of about0.01 to 5 weight percent, preferably about 0.01 to 1.5 weight percent.

Illustrative corrosion inhibitors include (short-chain) alkenyl succinicacids, partial esters thereof and nitrogen-containing derivativesthereof; and synthetic alkarylsulfonates, such as metaldinonylnaphthalene sulfonates. Corrosion inhibitors include, forexample, monocarboxylic acids which have from 8 to 30 carbon atoms,alkyl or alkenyl succinates or partial esters thereof, hydroxy-fattyacids which have from 12 to 30 carbon atoms and derivatives thereof,sarcosines which have from 8 to 24 carbon atoms and derivatives thereof,amino acids and derivatives thereof, naphthenic acid and derivativesthereof, lanolin fatty acid, mercapto-fatty acids and paraffin oxides.

Particularly preferred corrosion inhibitors are indicated below.Examples of monocarboxylic acids (C₈-C₃₀), Caprylic acid, pelargonicacid, decanoic acid, undecanoic acid, lauric acid, myristic acid,palmitic acid, stearic acid, arachic acid, behenic acid, cerotic acid,montanic acid, melissic acid, oleic acid, docosanic acid, erucic acid,eicosenic acid, beef tallow fatty acid, soy bean fatty acid, coconut oilfatty acid, linolic acid, linoleic acid, tall oil fatty acid,12-hydroxystearic acid, laurylsarcosinic acid, myritsylsarcosinic acid,palmitylsarcosinic acid, stearylsarcosinic acid, oleylsarcosinic acid,alkylated (C₈-C₂₀) phenoxyacetic acids, lanolin fatty acid and C₈-C₂₄mercapto-fatty acids.

Examples of polybasic carboxylic acids which function as corrosioninhibitors include alkenyl (C₁₀-C₁₀₀) succinic acids and esterderivatives thereof, dimer acid, N-acyl-N-alkyloxyalkyl aspartic acidesters (U.S. Pat. No. 5,275,749). Examples of the alkylamines whichfunction as corrosion inhibitors or as reaction products with the abovecarboxylates to give amides and the like are represented by primaryamines such as laurylamine, coconut-amine, n-tridecylamine,myristylamine, n-pentadecylamine, palmitylamine, n-heptadecylamine,stearylamine, n-nonadecylamine, n-eicosylamine, n-heneicosylamine,n-docosylamine, n-tricosylamine, n-pentacosylamine, oleylamine, beeftallow-amine, hydrogenated beef tallow-amine and soy bean-amine.Examples of the secondary amines include dilaurylamine,di-coconut-amine, di-n-tri decyl amine, dimyristylamine,di-n-pentadecylamine, dipalmitylamine, di-n-pentadecylamine,distearylamine, di-n-nonadecylamine, di-n-eicosylamine,di-n-heneicosylamine, di-n-docosylamine, di-n-tricosylamine,di-n-pentacosyl-amine, dioleylamine, di-beef tallow-amine,di-hydrogenated beef tallow-amine and di-soy bean-amine. Examples of theaforementioned N-alkylpolyalkyenediamines include: ethylenediamines suchas laurylethylenediamine, coconut ethylenediamine,n-tridecylethylenediamine-, myristylethylenediamine,n-pentadecylethylenedi amine, palmitylethylenediamine,n-heptadecylethylenediamine, stearylethylenediamine,n-nonadecylethylenediamine, n-eicosylethylenediamine,n-heneicosylethylenedi amine, n-docosylethylendiamine,n-tricosylethylenediamine, n-pentacosylethylenediamine,oleylethylenediamine, beef tallow-ethylenediamine, hydrogenated beeftallow-ethylenediamine and soy bean-ethylenediamine; propylenediaminessuch as laurylpropylenediamine, coconut propylenediamine,n-tridecylpropylenediamine, myristylpropylenediamine,n-pentadecylpropylenediamine, palmitylpropylenediamine,n-heptadecylpropylenedi amine, stearylpropylenediamine,n-nonadecylpropylenediamine, n-eicosylpropylenediamine,n-heneicosylpropylenediamine, n-docosylpropylendiamine,n-tricosylpropylenediamine, n-pentacosylpropylenediamine, diethylenetriamine (DETA) or triethylene tetramine (TETA), oleylpropylenediamine,beef tallow-propylenediamine, hydrogenated beef tallow-propylenediamineand soy bean-propylenediamine; butylenediamines such aslaurylbutylenediamine, coconut butylenediamine,n-tridecylbutylenediamine-myristylbutylenediamine,n-pentadecylbutylenediamine, stearylbutylenediamine,n-eicosylbutylenediamine, n-heneicosylbutylenedia-mine,n-docosylbutylendiamine, n-tricosylbutylenediamine,n-pentacosylbutylenediamine, oleylbutylenediamine, beeftallow-butylenediamine, hydrogenated beef tallow-butylenediamine and soybean butylenediamine; and pentylenediamines such aslaurylpentylenediamine, coconut pentylenediamine,myristylpentylenediamine, palmitylpentylenediamine,stearylpentylenediamine, oleyl-pentylenediamine, beeftallow-pentylenediamine, hydrogenated beef tallow-pentylenediamine andsoy bean pentylenediamine.

Other illustrative corrosion inhibitors include2,5-dimercapto-1,3,4-thiadiazoles and derivatives thereof,mercaptobenzothiazoles, alkyltriazoles and benzotriazoles. Examples ofdibasic acids useful as corrosion inhibitors, which may be used in thepresent disclosure, are sebacic acid, adipic acid, azelaic acid,dodecanedioic acid, 3-methyladipic acid, 3-nitrophthalic acid,1,10-decanedicarboxylic acid, and fumaric acid. The corrosion inhibitorscan be a straight or branch-chained, saturated or unsaturatedmonocarboxylic acid or ester thereof which may optionally be sulphurisedin an amount up to 35% by weight. Preferably the acid is a C₄ to C₂₂straight chain unsaturated monocarboxylic acid. The preferredconcentration of this additive is from 0.001% to 0.35% by weight of thetotal heat transfer fluid composition. The preferred monocarboxylic acidis sulphurised oleic acid. However, other suitable materials are oleicacid itself; valeric acid and erucic acid. An illustrative corrosioninhibitor includes a triazole as previously defined. The triazole shouldbe used at a concentration from 0.005% to 0.25% by weight of the totalcomposition. The preferred triazole is tolylotriazole which may beincluded in the compositions of the disclosure include triazoles,thiazoles and certain diamine compounds which are useful as metaldeactivators or metal passivators. Examples include triazole,benzotriazole and substituted benzotriazoles such as alkyl substitutedderivatives. The alkyl substituent generally contains up to 1.5 carbonatoms, preferably up to 8 carbon atoms. The triazoles may contain othersubstituents on the aromatic ring such as halogens, nitro, amino,mercapto, etc. Examples of suitable compounds are benzotriazole and thetolyltriazoles, ethylbenzotriazoles, hexylbenzotriazoles,octylbenzotriazoles, chlorobenzotriazoles and nitrobenzotriazoles.Benzotriazole and tolyltriazole are particularly preferred. A straightor branched chain saturated or unsaturated monocarboxylic acid which isoptionally sulphurised in an amount which may be up to 35% by weight; oran ester of such an acid; and a triazole or alkyl derivatives thereof,or short chain alkyl of up to 5 carbon atoms; n is zero or an integerbetween 1 and 3 inclusive; and is hydrogen, morpholino, alkyl, amido,amino, hydroxy or alkyl or aryl substituted derivatives thereof; or atriazole selected from 1,2,4 triazole, 1,2,3 triazole,5-anilo-1,2,3,4-thiatriazole, 3-amino-1,2,4 triazole,1-H-benzotriazole-1-yl-methylisocyanide, methylene-bis-benzotriazole andnaphthotriazole.

The corrosion inhibitors may be used in an amount of 0.01 to 5 wt %,preferably 0.01 to 1.5 wt %, more preferably 0.01 to 0.2 wt %, stillmore preferably 0.01 to 0.1 wt % (on an as-received basis) based on thetotal weight of the heat transfer fluid composition.

Antifoam Agents

Antifoam agents may advantageously be added to heat transfer fluidcompositions. These agents retard the formation of stable foams.Silicones and organic polymers are typical antifoam agents. For example,polysiloxanes, such as silicon oil or polydimethyl siloxane, provideantifoam properties. Antifoam agents are commercially available and maybe used in conventional minor amounts along with other additives such asdemulsifiers; usually the amount of these additives combined is lessthan 1 weight percent and often less than 0.1 weight percent. In anembodiment, such additives may be used in an amount of about 0.01 to 5weight percent, preferably 0.1 to 3 weight percent, more preferablyabout 0.5 to 1.5 weight percent.

Antiwear Additives

The heat transfer fluid compositions may include at least one antiwearagent. Examples of suitable antiwear agents include oil soluble aminesalts of phosphorus compounds, sulphurized olefins, metaldihydrocarbyldithio-phosphates (such as zinc dialkyldithiophosphates),thiocarbamate-containing compounds, such as thiocarbamate esters,thiocarbamate amides, thiocarbamic ethers, alkylene-coupledthiocarbamates, and bis(S-alkyldithiocarbamyl) disulphides.

Antiwear agents used in the formulation of the heat transfer fluid maybe ashless or ash-forming in nature. Preferably, the antiwear agent isashless. So called ashless antiwear agents are materials that formsubstantially no ash upon combustion. For example, non-metal-containingantiwear agents are considered ashless.

In one embodiment, oil soluble phosphorus amine antiwear agents includean amine salt of a phosphorus acid ester or mixtures thereof. The aminesalt of a phosphorus acid ester includes phosphoric acid esters andamine sails thereof dialkyldithiophosphoric acid esters and amine saltsthereof amine salts of phosphites; and amine salts ofphosphorus-containing carboxylic esters, ethers, and amides; andmixtures thereof. The amine salt of a phosphorus acid ester may be usedalone or in combination.

In one embodiment, oil soluble phosphorus amine salts include partialamine salt-partial metal salt compounds or mixtures thereof. In oneembodiment, the phosphorus compound further includes a sulphur atom inthe molecule. In one embodiment, the amine salt of the phosphoruscompound may be ashless, i.e., metal-free (prior to being mixed withother components).

The amines which may be suitable for use as the amine salt includeprimary amines, secondary amines, tertiary amines, and mixtures thereof.The amines include those with at least one hydrocarbyl group, or, incertain embodiments, two or three hydrocarbyl groups. The hydrocarbylgroups may contain 2 to 30 carbon atoms, or in other embodiments 8 to26, or 10 to 20, or 13 to 19 carbon atoms.

Primary amines include ethylamine, propylamine, butylamine,2-ethylhexylamine, octylamine, and dodecylamine, as well as such fattyamines as n-octylamine, n-decylamine, n-dodeclyamine, n-tetradecylamine,n-hexadecylamine, n-octadecylamine and oleyamine. Other useful fattyamines include commercially available fatty amines such as “Armeen™”amines (products available from Akzo Chemicals, Chicago, Ill.), such asArmeen C, Armeen O, Armeen O L, Armeen T, Armeen H T, Armeen S andArmeen S D, wherein the letter designation relates to the fatty group,such as coco, oleyl, tallow, or stearyl groups.

Examples of suitable secondary amines include dim ethylamine,diethylamine, dipropylamine, dibutylamine, diamylamine, dihexylamine,diheptylamine, methylethylamine, ethylbutylamine and ethylamylamine. Thesecondary amines may be cyclic amines such as piperidine, piperazine andmorpholine.

The amine may also be a tertiary-aliphatic primary amine. The aliphaticgroup in this case may be an alkyl group containing 2 to 30, or 6 to 26,or 8 to 24 carbon atoms. Tertiary alkyl amines include monoamines suchas tert-butylamine, tert-hexylamine, 1-methyl-1-amino-cyclohexane,tert-octylamine, tert-decylamine, tertdodecylamine,tert-tetradecylamine, tert-hexadecylamine, tert-octadecylamine,tert-tetracosanylamine, and tert-octacosanylamine.

In one embodiment, the phosphorus acid amine salt includes an amine withC₁₁ to C₁₄ tertiary alkyl primary groups or mixtures thereof. In oneembodiment the phosphorus acid amine salt includes an amine with C₁₄ toC₁₈ tertiary alkyl primary amines or mixtures thereof. In one embodimentthe phosphorus acid amine salt includes an amine with C₁₈ to C₂₂tertiary alkyl primary amines or mixtures thereof.

Mixtures of amines may also be used in the disclosure. In one embodimenta useful mixture of amines is “Primene™ 81R” and “Primene™ JMT.”Primene™ 81R and Primene™ JMT (both produced and sold by Rohm & Haas)are mixtures of C₁₁ to C₁₄ tertiary alkyl primary amines and C₁₈ to C₂₂tertiary alkyl primary amines respectively.

In one embodiment, oil soluble amine salts of phosphorus compoundsinclude a sulphur-free amine salt of a phosphorus-containing compoundmay be obtained/obtainable by a process comprising: reacting an aminewith either (i) a hydroxy-substituted di-ester of phosphoric acid, or(ii) a phosphorylated hydroxy-substituted di- or tri-ester of phosphoricacid. A more detailed description of compounds of this type is disclosedin International Application PCT/US08/051126.

In one embodiment, the hydrocarbyl amine salt of an alkylphosphoric acidester is the reaction product of a C₁₄ to C₁₈ alkylated phosphoric acidwith Primene 81RT™ (produced and sold by Rohm & Haas) which is a mixtureof C₁₁ to C₁₄ tertiary alkyl primary amines.

Examples of hydrocarbyl amine salts of dialkyldithiophosphoric acidesters include the reaction product(s) of isopropyl, methyl-amyl(4-methyl-2-pentyl or mixtures thereof), 2-ethylhexyl, heptyl, octyl ornonyl dithiophosphoric acids with ethylene diamine, morpholine, orPrimene 81R™, and mixtures thereof.

In one embodiment, the dithiophosphoric acid may be reacted with anepoxide or a glycol. This reaction product is further reacted with aphosphorus acid, anhydride, or lower ester. The epoxide includes analiphatic epoxide or a styrene oxide. Examples of useful epoxidesinclude ethylene oxide, propylene oxide, butene oxide, octene oxide,dodecene oxide, and styrene oxide. In one embodiment, the epoxide may bepropylene oxide. The glycols may be aliphatic glycols having from 1 to12, or from 2 to 6, or 2 to 3 carbon atoms. The dithiophosphoric acids,glycols, epoxides, inorganic phosphorus reagents and methods of reactingthe same are described in U.S. Pat. Nos. 3,197,405 and 3,544,465. Theresulting acids may then be salted with amines.

The dithiocarbamate-containing compounds may be prepared by reacting adithiocarbamate acid or salt with an unsaturated compound. Thedithiocarbamate containing compounds may also be prepared bysimultaneously reacting an amine, carbon disulphide and an unsaturatedcompound. Generally, the reaction occurs at a temperature from 25° C. to125° C.

Examples of suitable olefins that may be sulphurised to form thesulphurised olefin include propylene, butylene, isobutylene, pentene,hexane, heptene, octane, nonene, decene, undecene, dodecene, undecyl,tridecene, tetradecene, pentadecene, hexadecene, heptadecene,octadecene, octadecenene, nonodecene, eicosene or mixtures thereof. Inone embodiment, hexadecene, heptadecene, octadecene, octadecenene,nonodecene, eicosene or mixtures thereof and their dimers, trimers andtetramers are especially useful olefins. Alternatively, the olefin maybe a Diels-Alder adduct of a diene such as 1,3-butadiene and anunsaturated ester, such as, butylacrylate.

Another class of sulphurised olefin includes fatty acids and theiresters. The fatty acids are often obtained from vegetable oil or animaloil; and typically contain 4 to 22 carbon atoms. Examples of suitablefatty acids and their esters include triglycerides, oleic acid, linoleicacid, to palmitoleic acid or mixtures thereof. Often, the fatty acidsare obtained from lard oil, tall oil, peanut oil, soybean oil,cottonseed oil, sunflower seed oil or mixtures thereof. In oneembodiment fatty acids and/or ester are mixed with olefins.

Polyols include diols, triols, and alcohols with higher numbers ofalcoholic OH groups. Polyhydric alcohols include ethylene glycols,including di-, tri- and tetraethylene glycols; propylene glycols,including di-, tri- and tetrapropylene glycols; glycerol; butane diol;hexane diol; sorbitol; arabitol; mannitol; sucrose; fructose; glucose;cyclohexane diol; erythritol; and penta-erythritols, including di- andtripentaerythritol. Often the polyol is diethylene glycol, triethyleneglycol, glycerol, sorbitol, penta erythritol or dipentaerythritol.

In an alternative embodiment, the ashless antiwear agent may be amonoester of a polyol and an aliphatic carboxylic acid, often an acidcontaining 12 to 24 carbon atoms. Often the monoester of a polyol and analiphatic carboxylic acid is in the form of a mixture with a sunfloweroil or the like, which may be present in the mixture from 5 to 95, inseveral embodiments from 10 to 90, or from 20 to 85, or 20 to 80 weightpercent of said mixture. The aliphatic carboxylic acids (especially amonocarboxylic acid) which form the esters are those acids typicallycontaining 12 to 24, or from 14 to 20 carbon atoms. Examples ofcarboxylic acids include dodecanoic acid, stearic acid, lauric acid,behenic acid, and oleic acid.

Illustrative antiwear additives useful in this disclosure include, forexample, metal salts of a carboxylic acid. The metal is selected from atransition metal and mixtures thereof. The carboxylic acid is selectedfrom an aliphatic carboxylic acid, a cycloaliphatic carboxylic acid, anaromatic carboxylic acid, and mixtures thereof.

The metal is preferably selected from a Group 10, 11 and 12 metal, andmixtures thereof. The carboxylic acid is preferably an aliphatic,saturated, unbranched carboxylic acid having from about 8 to about 26carbon atoms, and mixtures thereof.

The metal is preferably selected from nickel (Ni), palladium (Pd),platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), andmixtures thereof.

The carboxylic acid is preferably selected from caprylic acid (C8),pelargonic acid (C9), capric acid (C10), undecylic acid (C11), lauricacid (C12), tridecylic acid (C13), myristic acid (C14), pentadecylicacid (C15), palmitic acid (C16), margaric acid (C17), stearic acid(C18), nonadecylic acid (C19), arachidic acid (C20), heneicosylic acid(C21), behenic acid (C22), tricosylic acid (C23), lignoceric acid (C24),pentacosylic acid (C25), cerotic acid (C26), and mixtures thereof.

Preferably, the metal salt of a carboxylic acid comprises zinc stearate,silver stearate, to palladium stearate, zinc palmitate, silverpalmitate, palladium palmitate, and mixtures thereof.

The metal salt of a carboxylic acid can be present in the heat transferfluid formulations of this disclosure in an amount of from about 0.01weight percent to about 5 weight percent, based on the total weight ofthe formulated oil.

A metal alkylthiophosphate and more particularly a metal dialkyl dithiophosphate in which the metal constituent is zinc, or zinc dialkyl dithiophosphate (ZDDP) can be a useful component of the heat transfer fluidsof this disclosure. ZDDP can be derived from primary alcohols, secondaryalcohols or mixtures thereof. ZDDP compounds generally are of theformula:Zn[SP(S)(OR¹)(OR²)]₂where R¹ and R² are C₁-C₁₈ alkyl groups, preferably C₂-C₁₂ alkyl groups.These alkyl groups may be straight chain or branched. Alcohols used inthe ZDDP can be 2-propanol, butanol, secondary butanol, pentanols,hexanols such as 4-methyl-2-pentanol, n-hexanol, n-octanol, 2-ethylhexanol, alkylated phenols, and the like. Mixtures of secondary alcoholsor of primary and secondary alcohol can be preferred. Alkyl aryl groupsmay also be used.

Preferable zinc dithiophosphates which are commercially availableinclude secondary zinc dithiophosphates such as those available from forexample, The Lubrizol Corporation under the trade designations “LZ677A”, “LZ 1095” and “LZ 1371”, from for example Chevron Oronite underthe trade designation “OLOA 262” and from for example Afton Chemicalunder the trade designation “HITEC 7169”.

The ZDDP is typically used in amounts of from about 0.4 weight percentto about 1.2 weight percent, preferably from about 0.5 weight percent toabout 1.0 weight percent, and more preferably from about 0.6 weightpercent to about 0.8 weight percent, based on the total weight of theheat transfer fluid, although more or less can often be usedadvantageously. Preferably, the ZDDP is a secondary ZDDP and present inan amount of from about 0.6 to 1.0 weight percent of the total weight ofthe heat transfer fluid.

Low phosphorus heat transfer fluid formulations are included in thisdisclosure. For such formulations, the phosphorus content is typicallyless than about 0.12 weight percent preferably less than about 0.10weight percent and most preferably less than about 0.085 weight percent.

Other illustrative antiwear agents useful in this disclosure include,for example, zinc alkyldithiophosphates, aryl phosphates and phosphites,sulfur-containing esters, phosphosulfur to compounds, and metal orash-free dithiocarbamates.

The antiwear additive concentration in the heat transfer fluids of thisdisclosure can range from about 0.01 to about 5 weight percent,preferably about 0.1 to 4.5 weight percent, and more preferably fromabout 0.2 weight percent to about 4 weight percent, based on the totalweight of the heat transfer fluid.

Other Additives

The formulated heat transfer fluid useful in the present disclosure mayadditionally contain one or more of the other commonly used heattransfer fluid performance additives including but not limited todispersants, detergents, viscosity modifiers, metal passivators, ionicliquids, extreme pressure additives, anti-seizure agents, wax modifiers,fluid-loss additives, seal compatibility agents, lubricity agents,anti-staining agents, chromophoric agents, defoamants, demulsifiers,emulsifiers, densifiers, wetting agents, gelling agents, tackinessagents, colorants, and others. For a review of many commonly usedadditives, see Klamann in Lubricants and Related Products, VerlagChemie, Deerfield Beach, Fla.; ISBN 0-89573-177-0; see also U.S. Pat.No. 7,704,930, the disclosure of which is incorporated herein in itsentirety. These additives are commonly delivered with varying amounts ofdiluent oil, that may range from 5 weight percent to 50 weight percent.

The additives useful in this disclosure do not have to be soluble in theheat transfer fluids. Insoluble additives such as zinc stearate in oilcan be dispersed in the heat transfer fluids of this disclosure.

The types and quantities of performance additives used in combinationwith the instant disclosure in heat transfer fluid compositions are notlimited by the examples shown herein as illustrations.

Dispersants

The heat transfer fluid compositions may include at least onedispersant. During electrical apparatus component operation,oil-insoluble oxidation byproducts are produced. Dispersants help keepthese byproducts in solution, thus diminishing their deposition on metalsurfaces. Dispersants used in the formulation of the heat transfer fluidmay be ashless or ash-forming in nature. Preferably, the dispersant isashless. So called ashless dispersants are organic materials that formsubstantially no ash upon combustion. For example, non-metal-containingor borated metal-free dispersants are considered ashless.

Suitable dispersants typically contain a polar group attached to arelatively high molecular weight hydrocarbon chain. The polar grouptypically contains at least one element of nitrogen, oxygen, orphosphorus. Typical hydrocarbon chains contain 50 to 400 carbon atoms.

A particularly useful class of dispersants are the (poly)alkenylsuccinicderivatives, typically produced by the reaction of a long chainhydrocarbyl substituted succinic compound, usually a hydrocarbylsubstituted succinic anhydride, with a polyhydroxy or polyaminocompound. The long chain hydrocarbyl group constituting the oleophilicportion of the molecule which confers solubility in the oil, is normallya polyisobutylene group. Many examples of this type of dispersant arewell known commercially and in the literature. Exemplary U.S. patentsdescribing such dispersants are U.S. Pat. Nos. 3,172,892; 3,2145,707;3,219,666; 3,316,177; 3,341,542; 3,444,170; 3,454,607; 3,541,012;3,630,904; 3,632,511; 3,787,374 and 4,234,435. Other types of dispersantare described in U.S. Pat. Nos. 3,036,003; 3,200,107; 3,254,025;3,275,554; 3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574;3,725,277; 3,725,480; 3,726,882; 4,454,059; 3,329,658; 3,449,250;3,519,565; 3,666,730; 3,687,849; 3,702,300; 4,100,082; 5,705,458. Afurther description of dispersants may be found, for example, inEuropean Patent Application No. 471 071, to which reference is made forthis purpose.

Hydrocarbyl-substituted succinic acid and hydrocarbyl-substitutedsuccinic anhydride derivatives are useful dispersants. In particular,succinimide, succinate esters, or succinate ester amides prepared by thereaction of a hydrocarbon-substituted succinic acid compound preferablyhaving at least 50 carbon atoms in the hydrocarbon substituent, with atleast one equivalent of an alkylene amine are particularly useful.

Succinimides are formed by the condensation reaction between hydrocarbylsubstituted succinic anhydrides and amines. Molar ratios can varydepending on the polyamine. For example, the molar ratio of hydrocarbylsubstituted succinic anhydride to TEPA can vary from about 1:1 to about5:1. Representative examples are shown in U.S. Pat. Nos. 3,087,936;3,172,892; 3,219,666; 3,272,746; 3,322,670; and 3,652,616, 3,948,800.

Succinate esters are formed by the condensation reaction betweenhydrocarbyl substituted succinic anhydrides and alcohols or polyols.Molar ratios can vary depending on the alcohol or polyol used. Forexample, the condensation product of a hydrocarbyl substituted succinicanhydride and pentaerythritol is a useful dispersant.

Succinate ester amides are formed by condensation reaction betweenhydrocarbyl substituted succinic anhydrides and alkanol amines. Forexample, suitable alkanol amines include ethoxylatedpolyalkylpolyamines, propoxylated polyalkylpolyamines andpolyalkenylpolyamines such as polyethylene polyamines. One example ispropoxylated hexamethylenediamine. Representative examples are shown inU.S. Pat. No. 4,426,305.

The molecular weight of the hydrocarbyl substituted succinic anhydridesused in the preceding paragraphs will typically range between 800 and2,500 or more. The above products can be post-reacted with variousreagents such as sulfur, oxygen, formaldehyde, carboxylic acids such asoleic acid. The above products can also be post reacted with boroncompounds such as boric acid, borate esters or highly borateddispersants, to form borated dispersants generally having from about 0.1to about 5 moles of boron per mole of dispersant reaction product.

Mannich base dispersants are made from the reaction of alkylphenols,formaldehyde, and amines. See U.S. Pat. No. 4,767,551, which isincorporated herein by reference. Process aids and catalysts, such asoleic acid and sulfonic acids, can also be part of the reaction mixture.Molecular weights of the alkylphenols range from 800 to 2,500.Representative examples are shown in U.S. Pat. Nos. 3,697,574;3,703,536; 3,704,308; 3,751,365; 3,756,953; 3,798,165; and 3,803,039.

Typical high molecular weight aliphatic acid modified Mannichcondensation products useful in this disclosure can be prepared fromhigh molecular weight alkyl-substituted hydroxyaromatics or HNR₂group-containing reactants.

Hydrocarbyl substituted amine ashless dispersant additives are wellknown to one skilled in the art; see, for example, U.S. Pat. Nos.3,275,554; 3,438,757; 3,565,804; 3,755,433, 3,822,209, and 5,084,197.

Illustrative dispersants include borated and non-borated succinimides,including those derivatives from mono-succinimides, bis-succinimides,and/or mixtures of mono- and bis-succinimides, wherein the hydrocarbylsuccinimide is derived from a hydrocarbylene group such aspolyisobutylene having a Mn of from about 500 to about 5000, or fromabout 1000 to about 3000, or about 1000 to about 2000, or a mixture ofsuch hydrocarbylene groups, often with high terminal vinylic groups.Other preferred dispersants include succinic acid-esters and amides,alkylphenol-polyamine-coupled Mannich adducts, their capped derivatives,and other related components.

Polymethacrylate or polyacrylate derivatives are another class ofdispersants. These dispersants are typically prepared by reacting anitrogen containing monomer and a methacrylic or acrylic acid esterscontaining 5-25 carbon atoms in the ester group. Representative examplesare shown in U.S. Pat. Nos. 2,100,993, and 6,323,164. Polymethacrylateand polyacrylate dispersants are normally used as multifunctionalviscosity modifiers. The lower molecular weight versions can be used asheat transfer fluid dispersants or fuel detergents.

Other illustrative dispersants useful in this disclosure include thosederived from polyalkenyl-substituted mono- or dicarboxylic acid,anhydride or ester, which dispersant has a polyalkenyl moiety with anumber average molecular weight of at least 900 and from greater than1.3 to 1.7, preferably from greater than 1.3 to 1.6, most preferablyfrom greater than 1.3 to 1.5, functional groups (mono- or dicarboxylicacid producing moieties) per polyalkenyl moiety (a medium functionalitydispersant). Functionality (F) can be determined according to thefollowing formula:F=(SAP×M_(n))/((112,200×A.I.)−(SAP×98))wherein SAP is the saponification number (i.e., the number of milligramsof KOH consumed in the complete neutralization of the acid groups in onegram of the succinic-containing reaction product, as determinedaccording to ASTM D94); M_(n) is the number average molecular weight ofthe starting olefin polymer; and A.I. is the percent active ingredientof the succinic-containing reaction product (the remainder beingunreacted olefin polymer, succinic anhydride and diluent).

The polyalkenyl moiety of the dispersant may have a number averagemolecular weight of at least 900, suitably at least 1500, preferablybetween 1800 and 3000, such as between 2000 and 2800, more preferablyfrom about 2100 to 2500, and most preferably from about 2200 to about2400. The molecular weight of a dispersant is generally expressed interms of the molecular weight of the polyalkenyl moiety. This is becausethe precise molecular weight range of the dispersant depends on numerousparameters including the type of polymer used to derive the dispersant,the number of functional groups, and the type of nucleophilic groupemployed.

Polymer molecular weight, specifically Mn, can be determined by variousknown techniques. One convenient method is gel permeation chromatography(GPC), which additionally provides molecular weight distributioninformation (see W. W. Yau, J. J. Kirkland and D. D. Bly, “Modern SizeExclusion Liquid Chromatography”, John Wiley and Sons, New York, 1979).Another useful method for determining molecular weight, particularly forlower molecular weight polymers, is vapor pressure osmometry (e.g., ASTMD3592).

The polyalkenyl moiety in a dispersant preferably has a narrow molecularweight distribution (MWD), also referred to as polydispersity, asdetermined by the ratio of weight average molecular weight (M_(w)) tonumber average molecular weight (M_(n)). Polymers having a M_(w)/M_(n)of less than 2.2, preferably less than 2.0, are most desirable. Suitablepolymers have a polydispersity of from about 1.5 to 2.1, preferably fromabout 1.6 to about 1.8.

Suitable polyalkenes employed in the formation of the dispersantsinclude homopolymers, interpolymers or lower molecular weighthydrocarbons. One family of such polymers comprise polymers of ethyleneand/or at least one C₃ to C₂₄ alpha-olefin. Preferably, such polymerscomprise interpolymers of ethylene and at least one alpha-olefin of theabove formula.

Another useful class of polymers is polymers prepared by cationicpolymerization of monomers such as isobutene and styrene. Commonpolymers from this class include polyisobutenes obtained bypolymerization of a C₄ refinery stream having a butene content of 35 to75% by wt., and an isobutene content of 30 to 60% by wt. A preferredsource of monomer for making poly-n-butenes is petroleum feedstreamssuch as Raffinate II. These feedstocks are disclosed in the art such asin U.S. Pat. No. 4,952,739. A preferred embodiment utilizespolyisobutylene prepared from a pure isobutylene stream or a Raffinate Istream to prepare reactive isobutylene polymers with terminal vinylideneolefins. Polyisobutene polymers that may be employed are generally basedon a polymer chain of from 1500 to 3000.

Dispersants that contain the alkenyl or alkyl group have an Mn value ofabout 500 to about 5000 and an Mw/Mn ratio of about 1 to about 5. Thepreferred Mn intervals depend on the chemical nature of the agentimproving filterability. Polyolefinic polymers suitable for the reactionwith maleic anhydride or other acid materials or acid forming materials,include polymers containing a predominant quantity of C₂ to C₅monoolefins, for example, ethylene, propylene, butylene, isobutylene andpentene. A highly suitable polyolefinic polymer is polyisobutene. Thesuccinic anhydride preferred as a reaction substance is PIBSA, that is,polyisobutenyl succinic anhydride.

If the dispersant contains a succinimide comprising the reaction productof a succinic anhydride with a polyamine, the alkenyl or alkylsubstituent of the succinic anhydride serving as the reaction substanceconsists preferably of polymerised isobutene having an Mn value of about1200 to about 2500. More advantageously, the alkenyl or alkylsubstituent of the succinic anhydride serving as the reaction substanceconsists in a polymerised isobutene having an Mn value of about 2100 toabout 2400. If the agent improving filterability contains an ester ofsuccinic acid comprising the reaction product of a succinic anhydrideand an aliphatic polyhydric alcohol, the alkenyl or alkyl substituent ofthe succinic anhydride serving as the reaction substance consistsadvantageously of a polymerised isobutene having an Mn value of 500 to1500. In preference, a polymerised isobutene having an Mn value of 850to 1200 is used.

The amides may be amides of mono- or polycarboxylic acids or reactivederivatives thereof. The amides may be characterized by a hydrocarbylgroup containing from about 6 to about 90 carbon atoms; each isindependently hydrogen or a hydrocarbyl, aminohydrocarbyl,hydroxyhydrocarbyl or a heterocyclic-substituted hydrocarbyl group,provided that both are not hydrogen; each is, independently, ahydrocarbylene group containing up to about 10 carbon atoms.

The amide can be derived from a monocarboxylic acid, a hydrocarbyl groupcontaining from 6 to about 30 or 38 carbon atoms and more often will bea hydrocarbyl group derived from a fatty acid containing from 12 toabout 24 carbon atoms.

An illustrative amide that is derived from a di- or tricarboxylic acid,will contain from 6 to about 90 or more carbon atoms depending on thetype of polycarboxylic acid. For example, when the amide is derived froma dimer acid, will contain from about 18 to about 44 carbon atoms ormore, and amides derived from trimer acids generally will contain anaverage of from about 44 to about 90 carbon atoms. Each is independentlyhydrogen or a hydrocarbyl, aminohydrocarbyl, hydroxyhydrocarbyl or aheterocyclic-substituted hydrocarbon group containing up to about 10carbon atoms. It may be independently heterocyclic substitutedhydrocarbyl groups wherein the heterocyclic substituent is derived frompyrrole, pyrroline, pyrrolidine, morpholine, piperazine, piperidine,pyridine, pipecoline, etc. Specific examples include methyl, ethyl,n-propyl, n-butyl, n-hexyl, hydroxymethyl, hydroxyethyl, hydroxypropyl,amino-methyl, aminoethyl, aminopropyl, 2-ethylpyridine,1-ethylpyrrolidine, 1-ethylpiperidine, etc.

Illustrative aliphatic monoamines include mono-aliphatic anddi-aliphatic-substituted amines wherein the aliphatic groups may besaturated or unsaturated and straight chain or branched chain. Suchamines include, for example, mono- and di-alkyl-substituted amines,mono- and dialkenyl-substituted amines, etc. Specific examples of suchmonoamines include ethyl amine, diethyl amine, n-butyl amine, di-n-butylamine, isobutyl amine, coco amine, stearyl amine, oleyl amine, etc. Anexample of a cycloaliphatic-substituted aliphatic amine is2-(cyclohexyl)-ethyl amine. Examples of heterocyclic-substitutedaliphatic amines include 2-(2-aminoethyl)-pyrrole,2-(2-aminoethyl)-1-methylpyrrole, 2-(2-aminoethyl)-1-methylpyrrolidineand 4-(2-aminoethyl)morpholine, 1-(2-aminoethyl)piperazine,1-(2-aminoethyl)piperidine, 2-(2-aminoethyl)pyridine,1-(2-aminoethyl)pyrrolidine, 1-(3-aminopropyl)imidazole,3-(2-aminopropyl)indole, 4-(3-aminopropyl)morpholine,1-(3-aminopropyl)-2-pipecoline, 1-(3-aminopropyl)-2-pyrrolidinone, etc.

Illustrative cycloaliphatic monoamines are those monoamines whereinthere is one cycloaliphatic substituent attached directly to the aminonitrogen through a carbon atom in the cyclic ring structure. Examples ofcycloaliphatic monoamines include cyclohexylamines, cyclopentylamines,cyclohexenylamines, cyclopentenylamines, N-ethyl-cyclohexylamine,dicyclohexylamines, and the like. Examples of aliphatic-substituted,aromatic-substituted, and heterocyclic-substituted cycloaliphaticmonoamines include propyl-substituted cyclohexylamines,phenyl-substituted cyclopentylamines, and pyranyl-substitutedcyclohexylamine.

Illustrative aromatic amines include those monoamines wherein a carbonatom of the aromatic ring structure is attached directly to the aminonitrogen. The aromatic ring will usually be a mononuclear aromatic ring(i.e., one derived from benzene) but can include fused aromatic rings,especially those derived from naphthalene. Examples of aromaticmonoamines include aniline, di-(para-methylphenyl)amine, naphthylamine,N-(n-butyl)-aniline, and the like. Examples of aliphatic-substituted,cycloaliphatic-substituted, and heterocyclic-substituted aromaticmonoamines are para-ethoxy-aniline, para-dodecylaniline,cyclohexyl-substituted naphthylamine, variously substitutedphenathiazines, and thienyl-substituted aniline.

Illustrative polyamines are aliphatic, cycloaliphatic and aromaticpolyamines analogous to the above-described monoamines except for thepresence within their structure of additional amino nitrogens. Theadditional amino nitrogens can be primary, secondary or tertiary aminonitrogens. Examples of such polyamines includeN-amino-propyl-cyclohexylamines, N,N′-di-n-butyl-paraphenylene diamine,bis-(para-aminophenyl)methane, 1,4-diaminocyclohexane, and the like.

Illustrative hydroxy-substituted amines are those having hydroxysubstituents bonded directly to a carbon atom other than a carbonylcarbon atom; that is, they have hydroxy groups capable of functioning asalcohols. Examples of such hydroxy-substituted amines includeethanolamine, di-(3-hydroxypropyl)-amine, 3-hydroxybutyl-amine,4-hydroxybutyl-amine, diethanolamine, di-(2-hydroxyamine,N-(hydroxypropyl)-propylamine, N-(2-methyl)-cyclohexylamine,3-hydroxycyclopentyl parahydroxyaniline, N-hydroxyethal piperazine andthe like.

In one embodiment, the amines are alkylene polyamines includinghydrogen, or a hydrocarbyl, amino hydrocarbyl, hydroxyhydrocarbyl orheterocyclic-substituted hydrocarbyl group containing up to about 10carbon atoms. Examples of such alkylene polyamines include methylenepolyamines, ethylene polyamines, butylene polyamines, propylenepolyamines, pentylene polyamines, hexylene polyamines, heptylenepolyamines, etc.

Alkylene polyamines include ethylene diamine, triethylene tetramine,propylene diamine, trimethylene diamine, hexamethylene diamine,decamethylene diamine, hexamethylene to diamine, decamethylene diamine,octamethylene diamine, di(heptamethylene) triamine, tripropylenetetramine, tetraethylene pentamine, trimethylene diamine, pentaethylenehexamine, di(trimethylene)triamine, and the like. Higher homologs as areobtained by condensing two or more of the above-illustrated alkyleneamines are useful, as are mixtures of two or more of any of theafore-described polyamines.

Ethylene polyamines, such as those mentioned above, are especiallyuseful for reasons of cost and effectiveness. Such polyamines aredescribed in detail under the heading “Diamines and Higher Amines” inThe Encyclopedia of Chemical Technology, Second Edition, Kirk andOthmer, Volume 7, pages 27-39, Interscience Publishers, Division of JohnWiley and Sons, 1965, which is hereby incorporated by reference for thedisclosure of useful polyamines. Such compounds are prepared mostconveniently by the reaction of an alkylene chloride with ammonia or byreaction of an ethylene imine with a ring-opening reagent such asammonia, etc. These reactions result in the production of the somewhatcomplex mixtures of alkylene polyamines, including cyclic condensationproducts such as piperazines.

Other useful types of polyamine mixtures are those resulting fromstripping of the above-described polyamine mixtures. In this instance,lower molecular weight polyamines and volatile contaminants are removedfrom an alkylene polyamine mixture to leave as residue what is oftentermed “polyamine bottoms”. In general, alkylene polyamine bottoms canbe characterized as having less than 2, usually less than 1% (by weight)material boiling below about 200° C. In the instance of ethylenepolyamine bottoms, which are readily available and found to be quiteuseful, the bottoms contain less than about 2% (by weight) totaldiethylene triamine (DETA) or triethylene tetramine (TETA). A typicalsample of such ethylene polyamine bottoms obtained from the Dow ChemicalCompany of Freeport, Tex. designated “E-100”. Gas chromatographyanalysis of such a sample showed it to contain about 0.93% “Light Ends”(most probably DETA), 0.72% TETA, 21.74% tetraethylene pentamine and76.61% pentaethylene hexamine and higher (by weight). These alkylenepolyamine bottoms include cyclic condensation products such aspiperazine and higher analogs of diethylene triamine, triethylenetetramine and the like.

Illustrative dispersants are selected from: Mannich bases that arecondensation reaction products of a high molecular weight phenol, analkylene polyamine and an aldehyde such as formaldehyde; succinic-baseddispersants that are reaction products of a olefin polymer and succinicacylating agent (acid, anhydride, ester or halide) further reacted withan organic hydroxy compound and/or an amine; high molecular weightamides and esters such as reaction products of a hydrocarbyl acylatingagent and a polyhydric aliphatic alcohol (such as glycerol,pentaerythritol or sorbitol). Ashless (metal-free) polymeric materialsthat usually contain an oil soluble high molecular weight backbonelinked to a polar functional group that associates with particles to bedispersed are typically used as dispersants. Zinc acetate capped, alsoany treated dispersant, which include borated, cyclic carbonate,end-capped, polyalkylene maleic anhydride and the like; mixtures of someof the above, in treat rates that range from about 0.1% up to 10-20% ormore. Commonly used hydrocarbon backbone materials are olefin polymersand copolymers, i.e., ethylene, propylene, butylene, isobutylene,styrene; there may or may not be further functional groups incorporatedinto the backbone of the polymer, whose molecular weight ranges from 300tp to 5000. Polar materials such as amines, alcohols, amides or estersare attached to the backbone via a bridge.

The dispersant(s) are preferably non-polymeric (e.g., mono- orbis-succinimides). Such dispersants can be prepared by conventionalprocesses such as disclosed in U.S. Patent Application Publication No.2008/0020950, the disclosure of which is incorporated herein byreference.

The dispersant(s) can be borated by conventional means, as generallydisclosed in U.S. Pat. Nos. 3,087,936, 3,254,025 and 5,430,105.

Such dispersants may be used in an amount of about 0.01 to 20 weightpercent or 0.01 to 10 weight percent, preferably about 0.5 to 8 weightpercent, or more preferably 0.5 to 4 weight percent. Or such dispersantsmay be used in an amount of about 2 to 12 weight percent, preferablyabout 4 to 10 weight percent, or more preferably 6 to 9 weight percent.On an active ingredient basis, such additives may be used in an amountof about 0.06 to 14 weight percent, preferably about 0.3 to 6 weightpercent. The hydrocarbon portion of the dispersant atoms can range fromC₆₀ to C₁₀₀₀, or from C₇₀ to C₃₀₀, or from C₇₀ to C₂₀₀. Thesedispersants may contain both neutral and basic nitrogen, and mixtures ofboth. Dispersants can be end-capped by borates and/or cyclic carbonates.Nitrogen content in the finished oil can vary from about 200 ppm byweight to about 2000 ppm by weight, preferably from about 200 ppm byweight to about 1200 ppm by weight. Basic nitrogen can vary from about100 ppm by weight to about 1000 ppm by weight, preferably from about 100ppm by weight to about 600 ppm by weight.

As used herein, the dispersant concentrations are given on an “asdelivered” basis. Typically, the active dispersant is delivered with aprocess oil. The “as delivered” dispersant typically contains from about20 weight percent to about 80 weight percent, or from about 40 weightpercent to about 60 weight percent, of active dispersant in the “asdelivered” dispersant product.

Detergents

The heat transfer fluid compositions may include at least one detergent.Illustrative detergents useful in this disclosure include, for example,alkali metal detergents, alkaline earth metal detergents, or mixtures ofone or more alkali metal detergents and one or more alkaline earth metaldetergents. A typical detergent is an anionic material that contains along chain hydrophobic portion of the molecule and a smaller anionic oroleophobic hydrophilic portion of the molecule. The anionic portion ofthe detergent is typically derived from an organic acid such as a sulfuracid, carboxylic acid (e.g., salicylic acid), phosphorous acid, phenol,or mixtures thereof. The counterion is typically an alkaline earth oralkali metal.

The detergent is preferably a metal salt of an organic or inorganicacid, a metal salt of a phenol, or mixtures thereof. The metal ispreferably selected from an alkali metal, an alkaline earth metal, andmixtures thereof. The organic or inorganic acid is selected from analiphatic organic or inorganic acid, a cycloaliphatic organic orinorganic acid, an aromatic organic or inorganic acid, and mixturesthereof.

The metal is preferably selected from an alkali metal, an alkaline earthmetal, and mixtures thereof. More preferably, the metal is selected fromcalcium (Ca), magnesium (Mg), and mixtures thereof.

The organic acid or inorganic acid is preferably selected from a sulfuracid, a carboxylic acid, a phosphorus acid, and mixtures thereof.

Preferably, the metal salt of an organic or inorganic acid or the metalsalt of a phenol comprises calcium phenate, calcium sulfonate, calciumsalicylate, magnesium phenate, magnesium sulfonate, magnesiumsalicylate, and mixtures thereof.

Salts that contain a substantially stochiometric amount of the metal aredescribed as neutral salts and have a total base number (TBN, asmeasured by ASTM D2896) of from 0 to 80. Many compositions areoverbased, containing large amounts of a metal base that is achieved byreacting an excess of a metal compound (a metal hydroxide or oxide, forexample) with an acidic gas (such as carbon dioxide). Useful detergentscan be neutral, mildly overbased, or highly overbased. These detergentscan be used in mixtures of neutral, overbased, highly overbased calciumsalicylate, sulfonates, phenates and/or magnesium salicylate,sulfonates, phenates. The TBN ranges can vary from low, medium to highTBN products, including as low as 0 to as high as 600. Preferably theTBN delivered by the detergent is between 1 and 20. More preferablybetween 1 and 12. Mixtures of low, medium, high TBN can be used, alongwith mixtures of calcium and magnesium metal based detergents, andincluding sulfonates, phenates, salicylates, and carboxylates. Adetergent mixture with a metal ratio of 1, in conjunction of a detergentwith a metal ratio of 2, and as high as a detergent with a metal ratioof 5, can be used. Borated detergents can also be used.

Alkaline earth phenates are another useful class of detergent. Thesedetergents can be made by reacting alkaline earth metal hydroxide oroxide (CaO, Ca(OH)₂, BaO, Ba(OH)₂, MgO, Mg(OH)₂, for example) with analkyl phenol or sulfurized alkylphenol. Useful alkyl groups includestraight chain or branched C₁-C₃₀ alkyl groups, preferably, C₄-C₂₀ ormixtures thereof.

Examples of suitable phenols include isobutylphenol, 2-ethylhexylphenol,nonylphenol, dodecyl phenol, and the like. It should be noted thatstarting alkylphenols may contain more than one alkyl substituent thatare each independently straight chain or branched and can be used from0.5 to 6 weight percent. When a non-sulfurized alkylphenol is used, thesulfurized product may be obtained by methods well known in the art.These methods include heating a mixture of alkylphenol and sulfurizingagent (including elemental sulfur, sulfur halides such as sulfurdichloride, and the like) and then reacting the sulfurized phenol withan alkaline earth metal base.

Metal salts of carboxylic acids are useful detergents. These carboxylicacid detergents may be prepared by reacting a basic metal compound withat least one carboxylic acid and removing free water from the reactionproduct. Detergents made from salicylic acid are one preferred class ofdetergents derived from carboxylic acids. Useful salicylates includelong chain alkyl salicylates. One useful family of compositions is ofthe formula

where R is an alkyl group having 1 to about 30 carbon atoms, n is aninteger from 1 to 4, and M is an alkaline earth metal. Preferred Rgroups are alkyl chains of at least C₁₁, preferably C₁₃ or greater. Rmay be optionally substituted with substituents that do not interferewith the detergent's function. M is preferably, calcium, magnesium, orbarium. More preferably, M is calcium.

Hydrocarbyl-substituted salicylic acids may be prepared from phenols bythe Kolbe reaction (see U.S. Pat. No. 3,595,791). The metal salts of thehydrocarbyl-substituted salicylic acids may be prepared by doubledecomposition of a metal salt in a polar solvent such as water oralcohol.

Alkaline earth metal phosphates are also used as detergents and areknown in the art.

Detergents may be simple detergents or what is known as hybrid orcomplex detergents. The latter detergents can provide the properties oftwo detergents without the need to blend separate materials. See U.S.Pat. No. 6,034,039.

Illustrative detergents include calcium alkylsalicylates, calciumalkylphenates and calcium alkarylsulfonates with alternate metal ionsused such as magnesium, barium, or sodium. Examples of the cleaning anddispersing agents which can be used include metal-based detergents suchas the neutral and basic alkaline earth metal sulphonates, alkalineearth metal phenates and alkaline earth metal salicylatesalkenylsuccinimide and alkenylsuccinimide esters and their borohydrides,phenates, salienius complex detergents and ashless dispersing agentswhich have been modified with sulphur compounds. These agents can beadded and used individually or in the form of mixtures, conveniently inan amount within the range of from 0.01 to 1 part by weight per 100parts by weight of base oil; these can also be high TBN, low TBN, ormixtures of high/low TBN.

Preferred detergents include calcium sulfonates, magnesium sulfonates,calcium salicylates, magnesium salicylates, calcium phenates, magnesiumphenates, and other related components (including borated detergents),and mixtures thereof. Preferred mixtures of detergents include magnesiumsulfonate and calcium salicylate, magnesium sulfonate and calciumsulfonate, magnesium sulfonate and calcium phenate, calcium phenate andcalcium salicylate, calcium phenate and calcium sulfonate, calciumphenate and magnesium salicylate, calcium phenate and magnesium phenate.

The detergent concentration in the heat transfer fluids of thisdisclosure can range from about 0.01 to about 10 weight percent,preferably about 0.1 to 7.5 weight percent, and more preferably fromabout 0.5 weight percent to about 5 weight percent, based on the totalweight of the heat transfer fluid.

As used herein, the detergent concentrations are given on an “asdelivered” basis. Typically, the active detergent is delivered with aprocess oil. The “as delivered” detergent typically contains from about20 weight percent to about 100 weight percent, or from about 40 weightpercent to about 60 weight percent, of active detergent in the “asdelivered” detergent product.

Viscosity Modifiers

Viscosity modifiers (also known as viscosity index improvers (VIimprovers), and viscosity improvers) can be included in the heattransfer fluid compositions of this disclosure.

Viscosity modifiers provide heat transfer fluids with high and lowtemperature operability. These additives impart shear stability atelevated temperatures and acceptable viscosity at low temperatures.

Suitable viscosity modifiers include high molecular weight hydrocarbons,polyesters and viscosity modifier dispersants that function as both aviscosity modifier and a dispersant. Typical molecular weights of thesepolymers are between about 10,000 to 1,500,000, more typically about20,000 to 1,200,000, and even more typically between about 50,000 and1,000,000.

Examples of suitable viscosity modifiers are linear or star-shapedpolymers and copolymers of methacrylate, butadiene, olefins, oralkylated styrenes. Polyisobutylene is a commonly used viscositymodifier. Another suitable viscosity modifier is polymethacrylate(copolymers of various chain length alkyl methacrylates, for example),some formulations of which also serve as pour point depressants. Othersuitable viscosity modifiers include copolymers of ethylene andpropylene, hydrogenated block copolymers of styrene and isoprene, andpolyacrylates (copolymers of various chain length acrylates, forexample). Specific examples include styrene-isoprene orstyrene-butadiene based polymers of 50,000 to 200,000 molecular weight.

Olefin copolymers are commercially available from Chevron OroniteCompany LLC under the trade designation “PARATONE®” (such as “PARATONE®8921” and “PARATONE® 8941”); from Afton Chemical Corporation under thetrade designation “HiTEC®” (such as “HiTEC® 5850B”; and from TheLubrizol Corporation under the trade designation “Lubrizol® 7067C”.Hydrogenated polyisoprene star polymers are commercially available fromInfineum International Limited, e.g., under the trade designation“SV200” and “SV600”. Hydrogenated diene-styrene block copolymers arecommercially available from Infineum International Limited, e.g., underthe trade designation “SV 50”.

The polymethacrylate or polyacrylate polymers can be linear polymerswhich are available from Evnoik Industries under the trade designation“Viscoplex®” (e.g., Viscoplex 6-954) or star polymers which areavailable from Lubrizol Corporation under the trade designation Asteric™(e.g., Lubrizol 87708 and Lubrizol 87725).

Illustrative vinyl aromatic-containing polymers useful in thisdisclosure may be derived predominantly from vinyl aromatic hydrocarbonmonomer. Illustrative vinyl aromatic-containing copolymers useful inthis disclosure may be represented by the following general formula:A−Bwherein A is a polymeric block derived predominantly from vinyl aromatichydrocarbon monomer, and B is a polymeric block derived predominantlyfrom conjugated diene monomer.

In an embodiment of this disclosure, the viscosity modifiers may be usedin an amount of less than about 10 weight percent, preferably less thanabout 7 weight percent, more preferably less than about 4 weightpercent, and in certain instances, may be used at less than 2 weightpercent, preferably less than about 1 weight percent, and morepreferably less than about 0.5 weight percent, based on the total weightof the formulated heat transfer fluid. Viscosity modifiers are typicallyadded as concentrates, in large amounts of diluent oil.

The viscosity modifiers may be used in an amount of 0.01 to 20 wt %,preferably 0.1 to 10 wt %, more preferably 0.5 to 7.5 wt %, still morepreferably 1 to 5 wt % (on an as-received basis) based on the totalweight of the heat transfer fluid composition.

As used herein, the viscosity modifier concentrations are given on an“as delivered” basis. Typically, the active polymer is delivered with adiluent oil. The “as delivered” viscosity modifier typically containsfrom 20 weight percent to 75 weight percent of an active polymer forpolymethacrylate or polyacrylate polymers, or from 8 weight percent to20 weight percent of an active polymer for olefin copolymers,hydrogenated polyisoprene star polymers, or hydrogenated diene-styreneblock copolymers, in the “as delivered” polymer concentrate.

Metal Passivators

The heat transfer fluid compositions may include at least one metalpassivator. The metal passivators/deactivators include, for example,benzotriazole, tolyltriazole, 2-mercaptobenzothiazole,dialkyl-2,5-dimercapto-1,3,4-thiadiazole;N,N′-disalicylideneethylenediamine,N,N′-disalicyli-denepropylenediamine; zinc dialkyldithiophosphates anddialkyl dithiocarbamates.

Some embodiments of the disclosure may further comprise a yellow metalpassivator. As used herein, “yellow metal” refers to a metallurgicalgrouping that includes brass and bronze alloys, aluminum bronze,phosphor bronze, copper, copper nickel alloys, and beryllium copper.

Typical yellow metal passivators include, for example, benzotriazole,totutriazole, tolyltriazole, mixtures of sodium tolutriazole andtolyltriazole, and combinations thereof. In one particular andnon-limiting embodiment, a compound containing tolyltriazole isselected. Typical commercial yellow metal passivators includeIRGAMET™-30, and IRGAMET™-42, available from Ciba Specialty Chemicals,now part of BASE, and VANLUBE™ 601 and 704, and CUVAN™ 303 and 484,available from R.T. Vanderbilt Company, Inc.

The metal passivator concentration in the heat transfer fluids of thisdisclosure can range from about 0.01 to about 5.0 weight percent,preferably about 0.01 to 3.0 weight percent, and more preferably fromabout 0.01 weight percent to about 1.5 weight percent, based on thetotal weight of the heat transfer fluid.

Ionic Liquids (ILs)

Ionic liquids are so-called salt melts which are preferably liquid atroom temperature and/or by definition have a melting point<100° C. Theyhave almost no vapor pressure and therefore have no cavitationproperties. In addition, through the choice of the cations and anions inthe ionic liquids, the lifetime of the heat transfer fluid is increased,and by adjusting the electric conductivity, these liquids can be used inequipment in which there is an electric charge buildup, e.g., electricvehicle components. Suitable cations for ionic liquids include aquaternary ammonium cation, a phosphonium cation, an imidazolium cation,a pyridinium cation, a pyrazolium cation, an oxazolium cation, apyrrolidinium cation, a piperidinium cation, a thiazolium cation, aguanidinium cation, a morpholinium cation, a trialkylsulfonium cation ora triazolium cation, which may be substituted with an anion selectedfrom the group consisting of [PF₆]⁻, [BF₄]³¹, [CF₃CO₂]³¹, [CF₃SO₃] aswell as its higher homologs, [C₄F₉—SO₃]³¹ or [C₈F₁₇—SO₃₁ and higherperfluoroalkylsulfonates, [(CF₃SO₂)₂N]⁻, [(CF₃SO₂)(CF₃COO)N]⁻,[R¹—SO₃]⁻, [R¹—O—SO₃]³¹, [R¹—COO]⁻, Cr, Br, [NO₃]⁻, [N(CN)₂]⁻, [HSO₄]⁻,PF_((6-x))R³ _(x) or [R¹R²PO₄]⁻ and the radicals R¹ and R² independentlyof one another are selected from hydrogen; linear or branched, saturatedor unsaturated, aliphatic or alicyclic alkyl groups with 1 to 20 carbonatoms; heteroaryl, heteroaryl-C₁-C₆-alkyl groups with 3 to 8 carbonatoms in the heteroaryl radical and at least one heteroatom of N, O andS, which may be combined with at least one group selected from C₁-C₆alkyl groups and/or halogen atoms; aryl-aryl C₁-C₆ alkyl groups with 5to 12 carbon atoms in the aryl radical, which may be substituted with atleast one C₁-C₆ alkyl group; R³ may be a perfluoroethyl group or ahigher perfluoroalkyl group, x is 1 to 4. However, other combinationsare also possible.

Ionic liquids with highly fluorinated anions are especially preferredbecause they usually have a high thermal stability. The water uptakeability may definitely be reduced by such anions, e.g., in the case ofthe bis(trifluoromethylsutfonyl)imide anion.

Illustrative ionic liquids include, for example,butylmethylpyrrolidinium bis(trifluoromethylsulfonyl)imide (MBPimide),methylpropylpyrrolidinium bis(trifluoromethylsulfonyl)imide (MPPimide),hexylmethylimidazolium to tris(perfluoroethyl)trifluorophosphate(HMIMPFET), hexylmethylimidazolium bis(trifluoromethylsulfonyl)imide(HMIMimide), hexylmethylpyrrolidinium bis(trifluoromethylsulfonyl)imide(HMP), tetrabutylphosphonium tris(perfluoroethyl)trifluorophosphate(BuPPFET), octylmethylimidazolium hexafluorophosphate (OMIM PF6),hexylpyridinium bis(trifluoromethyl)sulfonylimide (Hpyimide),methyltrioctylammonium trifluoroacetate (MOAac),butylmethylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate(MBPPFET), trihexyl(tetradecyl)phosphoniumbis(trifluoromethylsulfonyl)imide (HPDimide),1-ethyl-3-methylimidazolium ethyl sulfate (EMIM ethyl sulfate),1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide(EMIMimide), 1-ethyl-2,3-dimethylimidazoliumbis(trifluoromethylsulfonyl)imide (EMMIMimide),N-ethyl-3-methylpyridinium nonafluorobutanesulfonate (EMPyflate),trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)amide,trihexyl(tetradecyl)phosphoniumbis(2,4,4-trifluoromethylpentyl)phosphinate,tributyl(tetradecyl)phosphonium dodecylbenzenesulfonate, and the like.

Cation/anion combinations leading to ionic liquids include, for example,dialkylimidazolium, pyridinium, ammonium and phosphonium, etc. withorganic anions such as sulfonates, imides, methides, etc., as well asinorganic anions such as halides and phosphates, etc., such that anyother combination of cations and anions with which a low melting pointcan be achieved is also conceivable. Ionic liquids have an extremely lowvapor pressure, depending on their chemical structure, are nonflammableand often have thermal stability up to more than 260° C. and furthermoreare also suitable as heat transfer fluids.

The respective desired properties of the heat transfer fluids areachieved with the ionic liquids through a suitable choice of cations andanions. These desirable properties include adjusting electricalconductivity of the heat transfer fluid to spread the area of use,increasing the service life of the heat transfer fluid, and adjustingthe viscosity to improve the temperature suitability. Suitable cationsfor ionic liquids have proven to be a phosphonium cation, an imidazoliumcation, a pyridinium cation or a pyrrolidinium cation which may becombined with an anion containing fluorine and selected frombis(trifluoromethylsulfonyl)imide, bis(perfluoroalkylsulfonyl)imide,perfluoroalkyl sulfonate, tris(perfluoroalkyl)methidenes,bis(perfluoroalkyl)imidenes, bis(perfluoroaryl)imides,perfluoroarylperfluoroalkylsulfonylimides and tris(perfluoro-alkyl)trifluorophosphate or with a halogen-free alkyl sulfate anion.

Ionic liquids are preferred with highly fluorinated anions because theyusually have a high thermal stability. The water uptake ability may bereduced significantly by such anions, e.g., when usingbis(trifluoromethylsulfonyl) anion.

In an embodiment, such ionic liquid additives may be used in an amountof about 0.1 to 10 weight percent, preferably 0.5 to 7.5 weight percent,more preferably about 0.75 to 5 weight percent.

Antistatic Additives

In electrical apparatus components, static electricity is generated,especially when the heat transfer fluid is in use. To reduce thathazard, a conductive antistatic additive can be added to and distributedthroughout the heat transfer fluid. This heat transfer fluid willthereby avoid reduction in its performance associated with localbreakdown of the base stock and safety problems from static electricbuild-up.

A class of products called “antistatic fluids” or “antistaticadditives”, which also are petroleum distillates, can be added to adjustthe conductivity of a heat transfer fluid to safe levels, e.g., at orabove 100 pico-siemens per meter conductivity. Very small quantities ofthese antistatic fluids are required to raise the conductivity to thedesired levels, namely, some 10 to 30 milliliters per 1,000 gallons ofhydrocarbon.

According to another feature of the disclosure, the antistatic additiveis selected from a population of commercially available materials basedon the ability of the material's chemical compatibility with the heattransfer fluid and the cost effectiveness of adjusting the conductivityof the heat transfer fluid to the desired level for the heat transferfluid's anticipated application.

Typical antistatic fluids are ExxonMobil™ Chemical's line ofde-aromatized hydrocarbon fluids known as Exxsol™ fluids. Representativefluids and their distillation points include Exxsol™ antistatic fluidshexane (65 IBP (° C.) min, 71 DP (° C.) max, and additive amount 30ml/1000 gal), D 40 (150 IBP (° C.) min, 210 DP (° C.) max, and additiveamount 30 ml/1000 gal), D 3135 (152 IBP (° C.) min, 182 DP (° C.) max,and additive amount 10 ml/1000 gal), and D 60 (177 IBP (° C.) min, 220DP (° C.) max, and additive amount 30 ml/1000 gal). The IBP is thetemperature at which 1% of the material is distilled, and the DP is thetemperature at which 96% of the material is distilled.

Other illustrative antistatic agents are based on long-chain aliphaticamines (optionally ethoxylated) and amides, quaternary ammonium salts(e.g., behentrimonium chloride or cocamidopropyl betaine), esters ofphosphoric acid, polyethylene glycol esters, or polyols. Additionalantistatic agents include long-chain alkyl phenols, ethoxylated amines,glycerol esters, such as glycerol monostearate, amides, glycols, andfatty acids.

The quantity of antistatic additive required to adjust the conductivityof the heat transfer to fluid is determined by measuring theconductivity of the heat transfer fluid as the antistatic additive ismixed in and stopping when the desired conductivity consistent with theapplication to be reached. The amount of antistatic additive mixed inwill range between 0.001% and 10% of the heat transfer fluid by weight,and preferentially between 1% and 7.5% by weight, though it may be mixedin at a liquid volume of between 10 and 100,000 parts per million.

Pour Point Depressants (PPDs)

Conventional pour point depressants (also known as lube oil flowimprovers) may be added to the heat transfer fluid compositions of thepresent disclosure if desired. These pour point depressant may be addedto heat transfer fluid compositions of the present disclosure to lowerthe minimum temperature at which the fluid will flow or can be poured.Examples of suitable pour point depressants include polymethacrylates,polyacrylates, polyarylamides, condensation products of haloparaffinwaxes and aromatic compounds, vinyl carboxylate polymers, andterpolymers of dialkylfumarates, vinyl esters of fatty acids and allylvinyl ethers. U.S. Pat. Nos. 1,815,022; 2,015,748; 2,191,498; 2,387,501;2,655, 479; 2,666,746; 2,721,877; 2,721,878; and 3,250,715 describeuseful pour point depressants and/or the preparation thereof. Suchadditives may be used in an amount of about 0.01 to 5 weight percent,preferably 0.1 to 3 weight percent, more preferably about 0.5 to 1.5weight percent.

Seal Compatibility Agents

The heat transfer fluid compositions can include at least one sealcompatibility agent. Seal compatibility agents help to swell elastomericseals by causing a chemical reaction in the fluid or physical change inthe elastomer. Suitable seal compatibility agents for heat transferfluids include organic phosphates, aromatic esters, aromatichydrocarbons, esters (butylbenzyl phthalate, for example), andpolybutenyl succinic anhydride. Such additives may be used in an amountof about 0.01 to 5 weight percent, preferably 0.1 to 3 weight percent,more preferably about 0.5 to 1.5 weight percent.

Friction Modifiers

The heat transfer fluid compositions can include at least one frictionmodifier. A friction modifier is any material or materials that canalter the coefficient of friction of a surface. Friction modifiers, alsoknown as friction reducers, or lubricity agents or oiliness agents, andother such agents that change the ability of base oils, formulated heattransfer fluid compositions, or functional fluids, to modify thecoefficient of friction of a surface may be effectively used incombination with the base oils or heat transfer fluid compositions ofthe present disclosure if desired. Friction modifiers that lower thecoefficient of friction are particularly advantageous in combinationwith the base oils and lube compositions of this disclosure.

Illustrative friction modifiers may include, for example, organometalliccompounds or materials, or mixtures thereof. Illustrative organometallicfriction modifiers useful in the heat transfer fluid formulations ofthis disclosure include, for example, molybdenum amine, molybdenumdiamine, an organotungstenate, a molybdenum dithiocarbamate, molybdenumdithiophosphates, molybdenum amine complexes, molybdenum carboxylates,and the like, and mixtures thereof. Similar tungsten based compounds maybe preferable.

Other illustrative friction modifiers useful in the heat transfer fluidformulations of this disclosure include, for example, alkoxylated fattyacid esters, alkanolamides, polyol fatty acid esters, borated glycerolfatty acid esters, fatty alcohol ethers, and mixtures thereof.

Illustrative alkoxylated fatty acid esters include, for example,polyoxyethylene stearate, fatty acid polyglycol ester, and the like.These can include polyoxypropylene stearate, polyoxybutylene stearate,polyoxyethylene isosterate, polyoxypropylene isostearate,polyoxyethylene palmitate, and the like.

Illustrative alkanolamides include, for example, lauric aciddiethylalkanolamide, palmic acid diethylalkanolamide, and the like.These can include oleic acid diethyalkanolamide, stearic aciddiethylalkanolamide, oleic acid diethylalkanolamide, polyethoxylatedhydrocarbylamides, polypropoxylated hydrocarbylamides, and the like.

Illustrative polyol fatty acid esters include, for example, glycerolmono-oleate, saturated mono-, di-, and tri-glyceride esters, glycerolmono-stearate, and the like. These can include polyol esters,hydroxyl-containing polyol esters, and the like.

Illustrative borated glycerol fatty acid esters include, for example,borated glycerol mono-oleate, borated saturated mono-, di-, andtri-glyceride esters, borated glycerol mono-sterate, and the like. Inaddition to glycerol polyols, these can include trimethylolpropane,pentaerythritol, sorbitan, and the like. These esters can be polyolmonocarboxylate esters, polyol dicarboxylate esters, and on occasionpolyoltricarboxylate esters. Preferred can be the glycerol mono-oleates,glycerol dioleates, glycerol trioleates, glycerol monostearates,glycerol distearates, and glycerol tristearates and the correspondingglycerol monopalmitates, glycerol dipalmitates, and glyceroltripalmitates, and the respective isostearates, linoleates, and thelike. On occasion the glycerol esters can be preferred as well asmixtures containing any of these. Ethoxylated, propoxylated, butoxylatedfatty acid esters of polyols, especially using glycerol as underlyingpolyol can be preferred.

Illustrative fatty alcohol ethers include, for example, stearyl ether,myristyl ether, and the like. Alcohols, including those that have carbonnumbers from C₃ to C₅₀, can be ethoxylated, propoxylated, or butoxylatedto form the corresponding fatty alkyl ethers. The underlying alcoholportion can preferably be stearyl, myristyl, C₁₁-C₁₃ hydrocarbon, oleyl,isosteryl, and the like.

The heat transfer fluids of this disclosure exhibit desired properties,e.g., wear control, in the presence or absence of a friction modifier.

Useful concentrations of friction modifiers may range from 0.01 weightpercent to 5 weight percent, or about 0.1 weight percent to about 2.5weight percent, or about 0.1 weight percent to about 1.5 weight percent,or about 0.1 weight percent to about 1 weight percent. Concentrations ofmolybdenum-containing materials are often described in terms of Mo metalconcentration. Advantageous concentrations of Mo may range from 25 ppmto 700 ppm or more, and often with a preferred range of 50-200 ppm.Friction modifiers of all types may be used alone or in mixtures withthe materials of this disclosure. Often mixtures of two or more frictionmodifiers, or mixtures of friction modifier(s) with alternate surfaceactive material(s), are also desirable.

Extreme Pressure Agents

The heat transfer fluid compositions can include at least one extremepressure agent (EP). EP agents that are soluble in the oil includesulphur- and chlorosulphur-containing EP agents, chlorinated hydrocarbonEP agents and phosphorus EP agents. Examples of such EP agents includechlorinated wax; sulphurised olefins (such as sulphurised isobutylene),organic sulphides and polysulphides such as dibenzyldisulphide,bis-(chlorobenzyl)disulphide, dibutyl tetrasulphide, sulphurised methylester of oleic acid, sulphurised alkylphenol, sulphurised dipentene,sulphurised terpene, and sulphurised Diels-Alder adducts;phosphosulphurised hydrocarbons such as the reaction product ofphosphorus sulphide with turpentine or methyl oleate; phosphorus esterssuch as the dihydrocarbon and trihydrocarbon phosphites, e.g., dibutylphosphite, diheptyl phosphite, dicyclohexyl phosphite, pentylphenylphosphite; dipentylphenyl phosphite, tridecyl phosphite, distearylphosphite and polypropylene substituted phenol phosphite; metalthiocarbamates such as zinc dioctyldithio carbamate and bariumheptylphenol diacid; amine salts of alkyl and dialkylphosphoric acids orderivatives; and mixtures thereof (as described in U.S. Pat. No.3,197,405).

The extreme pressure agents may be used in an amount of 0.01 to 5 wt %,preferably 0.01 to 1.5 wt %, more preferably 0.01 to 0.2 wt %, stillmore preferably 0.01 to 0.1 wt % (on an as-received basis) based on thetotal weight of the heat transfer fluid composition.

Nanomaterials and Nanoparticles

The heat transfer fluids can include nanomaterials and/or nanoparticles.The nanomaterials and/or nanoparticles can advantageously alter the heattransfer properties of the heat transfer fluids of this disclosure.

The heat transfer fluids of this disclosure can exhibit advantaged heattransfer performance and properties in combination with engineerednanomaterials, nanomaterials, and nanoparticles.

Engineered nanomaterials, also known as nanomaterials, are materialscomprising nanoparticles that are small-scale assemblies of atoms and/ormolecules and that are produced to have unique/novel properties that aredifferent from those of the corresponding bulk materials.

Nanoparticles are particles having one or more dimensions that are inthe size range of about 1 nm to about 100 nm (nm=nanometers). In oneaspect, a nanoparticle may be considered to act without consideration ofa surrounding interfacial layer. In another aspect, a nanoparticle maybe considered to act including the effects of an interfacial layer.

Nanomaterial and nanoparticle compositions comprise, for example,metals, (e.g. Au, Ag, Pd, Pt, Cu, Fe, combinations thereof, and thelike), non-metals (e.g. C, B, Si, O, P, N, halides, combinationsthereof, and the like), metalloids, metal alloys, intermetallics,conductors, semiconductors, insulators, electroactive materials;optically active, electro-optical, polarizing, polarizable materials;magnetic, ferromagnetic, diamagnetic, electromagnetic, non-magneticmaterials; organics, heteroatom-containing organics, organometallics;inorganics, ceramics, metal oxides (e.g. Ti oxide, Zn oxide, Ce oxides,and the like); salts, complex salts, detergent-metal salt complexes,detergent-metal carbonate complexes, overbased detergent complexes,micellar-metal salt complexes, micellar-metal carbonate complexes, andcombinations thereof; single crystal, multi-crystal, multi-crystalline,semi-crystalline, amorphous, semi-amorphous, glassy, combinationsthereof, and the like.

Nanomaterials and nanoparticles also include, for example, agglomeratedmaterials, non-agglomerated materials; hydrophobic soluble, insoluble,partially soluble materials; hydrophilic soluble, insoluble, partiallysoluble materials; fulleranes, fullerenes, functionalized derivativesthereof; carboranes, boranes, borates, boramines; boron-carbon,boron-heteraoatom, boron-metal/metalloid complexes; graphene,functionalized derivatives thereof; single-carbon-atom sheet ormulti-sheet materials, functionalized derivatives thereof; singlewalled, seamless, cylindrical carbon nanotubes, functionalizedderivatives thereof; nanotubes and functionalized derivatives thereof,containing e.g. carbon, boron, nitrides, heteroatoms, combinationsthereof, and the like; nanotubes and functionalized derivatives thereof,that are e.g. single walled, multi-walled, coaxial, rolled scroll,uncapped, end-capped, and the like; nanowires and functionalizedderivatives thereof, containing e.g. carbon, boron, nitrides,heteroatoms, combinations thereof, and the like; quantum dots comprisinge.g. semiconductors, Cd selenide, Cd telluride, and the like; molecularsheets, that are e.g. single-layered, multi-layered, inter-layered,laminated, rolled, rolled scrolled, folded, intercalated, plates,platelets, and the like; nanowires that are e.g. molecular strings,molecular wires, molecular ropes, molecular cables, coaxial cables,single and multiple wires, coiled, spiraled, interwoven, and the like;core-shell, core-coated, surface modified, surface functionalized;morphologies, in some instances, having aspect ratios that are low inall dimensions, e.g. approaching 1, and in other instances, morphologieshaving aspect ratios that are high for at least one pair of dimensions,e.g. greater than 1, greater than 5, greater than 10, greater than 50,greater than 100, greater than 500, or even greater than 1000.

Suitable nanomaterials and nanoparticles are prepared for example bysynthesis, chemical reactions, nucleation and crystal growth;crystallization, precipitation; complexation; acid-base reactions;solubilization of metal salts, metal oxides, metal carbonates;carboxylic acid-base reactions; carboxylic acid or carboxylate saltsolubilization of metal salts, metal oxides, metal carbonates;metal-carboxylate overbasing; detergent metal-carbonate overbasing;liquid deposition; physical processes of milling, grinding, pulverizing,etc. of bulk materials; colloid processes; jet extrusions, aerosoling,vaporization, vapor deposition, ion beam decomposition; physicalseparations, chemical separations; deconstruction, decomposition,digestion, delamination, intercalation, etc. of bulk materials;combinations thereof, and the like.

Incorporation of nanomaterials and nanoparticles into heat transferfluids is improved as needed by use of one or more suitablecompatibilizing agents, including for example, solvents, dispersants,detergents, overbased detergents, solubilizing agents; complexingagents, complexing agents having electron donating groups including forexample, O, S, N, P—O, heteroatom functional groups, anions, and thelike; complexing agents having electron accepting groups including forexample, metals, metalloids, B, P, Si, cations, alkali and alkalineearth ions, complex cations, and the like; micelles, micellar complexes,micellar-metal salt complexes, detergent-metal salt complexes, overbaseddetergent complexes; ionic liquids; hydrocarbyl base oils containing forexample, aromatics, heteroaromatics, heteroatoms, polar functionalgroups, polarizable groups and structures, alcohols, ethers, polyethers,esters, polyesters, carbonates, polycarbonates, amines, polyamines,amides, polyamides, ureas, carboxyl groups, carboxylates, combinationsthereof, and the like.

Heat transfer fluids containing nanomaterials and nanoparticles may haveadvantaged performances and properties including, for example, extendedservice life, improved oxidation stability, improved thermal stability,improved wear protection, improved extreme pressure wear protection,improved cleanliness, controlled friction, controlled thermalconductivity, controlled heat capacity, controlled electricalconductivity.

The nanomaterials and nanoparticles may be used in an amount of 0.01 to20 wt %, preferably 0.1 to 10 wt %, more preferably 0.5 to 7.5 wt %,still more preferably 1 to 5 wt % (on an as-received basis) based on thetotal weight of the heat transfer fluid composition.

When heat transfer fluid compositions contain one or more of theadditives discussed above, the additive(s) are blended into thecomposition in an amount sufficient for it to perform its intendedfunction. Typical amounts of such additives useful in the presentdisclosure are shown in Table 3 below.

It is noted that many of the additives are shipped from the additivemanufacturer as a concentrate, containing one or more additivestogether, with a certain amount of base oil diluents. Accordingly, theweight amounts in the Table 3 below, as well as other amounts mentionedherein, are directed to the amount of active ingredient (that is thenon-diluent portion of the ingredient). The weight percent (wt %)indicated below is based on the total weight of the heat transfer fluidcomposition.

TABLE 3 Typical Amounts of Heat transfer fluid Components ApproximateApproximate Compound wt % (Useful) wt % (Preferred) Antioxidant 0.01-50.1-1.5 Corrosion Inhibitor 0.01-5 0.1-2   Antifoam Agent    0-30.001-0.15 

The foregoing additives are all commercially available materials. Theseadditives may be added independently but are usually precombined inpackages which can be obtained from suppliers of heat transfer fluidadditives. Additive packages with a variety of ingredients, proportionsand characteristics are available and selection of the appropriatepackage will take the requisite use of the ultimate composition intoaccount.

A block diagram of a computer related system 300 useful in thisdisclosure is shown in FIG. 3. System 300 includes a computer 305coupled to a network 330, e.g., the Internet.

Computer 305 includes a user interface 310, a processor 315, and amemory 320. Computer 305 may be implemented on a general-purposemicrocomputer. Although computer 305 is represented herein as astandalone device, it is not limited to such, but instead can be coupledto other devices (not shown) via network 330.

Processor 315 is configured of logic circuitry that responds to andexecutes instructions.

Memory 320 stores data and instructions for controlling the operation ofprocessor 315. Memory 320 may be implemented in a random access memory(RAM), a hard drive, a read only memory (ROM), or a combination thereof.One of the components of memory 320 is a program module 325.

Program module 325 contains instructions for controlling processor 315to execute the methods described herein. For example, as a result ofexecution of program module 325, processor 315 determines thedimensional effectiveness factor (DEF_(fluid)) of the heat transferfluid, the dimensional effectiveness factor (DEF_(reference)) of thereference fluid, and the normalized effectiveness factor (NEF_(fluid))of the heat transfer fluid. The term “module” is used herein to denote afunctional operation that may be embodied either as a stand-alonecomponent or as an integrated configuration of a plurality ofsub-ordinate components. Thus, program module 325 may be implemented asa single module or as a plurality of modules that operate in cooperationwith one another. Moreover, although program module 325 is describedherein as being installed in memory 320, and therefore being implementedin software, it could be implemented in any of hardware (e.g.,electronic circuitry), firmware, software, or a combination thereof.

User interface 310 includes an input device, such as a keyboard orspeech recognition subsystem, for enabling a user to communicateinformation and command selections to processor 315. User interface 310also includes an output device such as a display or a printer. A cursorcontrol such as a mouse, track-ball, or joy stick, allows the user tomanipulate a cursor on the display for communicating additionalinformation and command selections to processor 315.

Processor 315 outputs, to user interface 310, a result of an executionof the methods described herein. Alternatively, processor 315 coulddirect the output to a remote device (not shown) via network 330.

While program module 325 is indicated as already loaded into memory 320,it may be configured on a storage medium 335 for subsequent loading intomemory 320. Storage medium 335 can be any conventional storage mediumthat stores program module 325 thereon in tangible form. Examples ofstorage medium 335 include a floppy disk, a compact disk, a magnetictape, a read only memory, an optical storage media, universal serial bus(USB) flash drive, a digital versatile disc, or a zip drive.Alternatively, storage medium 335 can be a random access memory, orother type of electronic storage, located on a remote storage system andcoupled to computer 305 via network 330.

In an embodiment, the computer related system 300 can include one ormore databases configured to store and arrange data in said memory andto interact with the processor. The data includes at least one fluidproperty selected from the group consisting of density (ρ), specificheat (c_(p)), thermal conductivity (k), and dynamic viscosity (μ).

An illustrative heat transfer circuit 400 of this disclosure is depictedin FIG. 4. An element 405 (with heat transfer area A_(bot)) is to becooled, where a rate of heat conveyance, Q, is required to maintain theelement 405 at a temperature of Te. This heat is removed by circulatinga fluid with a heat capacity C_(p) and where the cool fluid enters theelement 405 with a temperature of Tc, and leaves the element 405 to becooled at a temperature Th. The hot fluid then rejects its heat via anelement 410, similar to a radiator. This element 410 could reject heatto another heat transfer fluid, or, as illustrated, to air at ambienttemperature, Ta. This heat rejection element 410 (with heat transferarea A_(cold)) could be a specific device, or, simply heat lost to theatmosphere as the fluid flows through piping. A pump 415 circulates thefluid, at a mass flowrate of {dot over (m)}. At steady state, the rateof heat conveyance is determined by the following equation:=Q={dot over (m)}°c _(p)°(Th°−Tc)={dot over (V)}ρ°c _(p)°(Th°−Tc)where {dot over (V)} is the volumetric flowrate and ρ is the fluiddensity.

Within the heat transfer circuit 400, cooling of the device can bedominated by the ability of the fluid to “convey heat” from the element405, or, can be dominated by the “localized heat transfer” mechanismswithin element 405. Many different equipment design and operationfactors can dictate which of these two phenomena are dominant. Forexample, in element 405 (i.e., the element to be cooled), localized heattransfer could be enhanced by the inclusion of cooling fins in theequipment design which increases the effective heat transfer area.Similarly, localized heat transfer could be improved by the artificialinduction of turbulence or boosted by enhancing fluid/hardware contactvia fluid jet flow within the element. For any specific system, whetherdue to basic design or through targeted design enhancements, it ispossible that this localized heat transfer is not the dominant mechanismcontrolling heat transfer performance, but instead, the fluid'sperformance is dominated by the ability of the fluid to convey heat awayfrom the element. The maximum amount of heat that could be conveyed bythe fluid is given by:Q _(max) ={dot over (V)}ρc _(p)(Te−Ta)

The actual heat conveyed from element 405 is given by:Q _(actual) ={dot over (V)}ρc _(p)(Th−Tc)

The system is considered to be dominated by localized heat transfer ifthe actual heat being conveyed is less than or equal to half of maximumamount of heat that could be conveyed, i.e.,

$\frac{Q_{actual}}{Q_{\max}} \leq {0.5 -^{``}{{Localized}\mspace{14mu}{heat}\mspace{14mu}{transfer}\mspace{14mu}{dominated}^{''}}}$

Conversely, if the actual amount of heat conveyed is more than half ofthe maximum possible amount of heat that could be conveyed by the fluid,the system is considered to be dominated by “heat conveyance”, i.e.,

$\frac{Q_{actual}}{Q_{\max}} > {{.05} -^{``}{{Heat}\mspace{14mu}{conveyance}\mspace{14mu}{dominated}^{''}}}$

Since the Mouromtseff number, Mo, attempts to relate the fluid'slocalized heat transfer coefficient to fluid properties, historicdiscussions regarding heat transfer fluids which refer to the Mo areonly meaningful in “localized heat transfer dominated” application, andbear little relevance in “heat conveyance dominated” applications.Further, it should be noted that unlike the Mo, the DEF and NEFeffectiveness factors described herein capture both the heat transferperformance and the energy required to circulate the fluid.

The following non-limiting examples are provided to illustrate thedisclosure.

EXAMPLES

Case 1

In the electric vehicle design addressed in this Case 1, there is alarge surface area across which heat is removed from hot surfaces. Thisis the case when, for instance, the battery to be cooled has a largesurface area available for cooling. As a result, the amount of heat flowfrom the hot surface to the heat transfer fluid is heat conveyancedominated. In the vehicle design addressed in this Case 1, the coolingcircuit design produces transitional flow (Reynolds number betweenaround 2100 and around 4000) dominates in the overall system, in orderto achieve a balance between the pressure required to circulate the heattransfer fluid and the size and weight of the cooling system. Finally,in the vehicle design addressed in this Case 1, a constant flow(positive displacement) pump is employed, such that the volume of heattransfer fluid being pumped through the system is independent of theproperties of the heat transfer fluid.

As a result, in this type of electric vehicle, the normalizedeffectiveness factor (NEF_(fluid)) will be proportional to the followingcombination of heat transfer fluid properties:ρ^(0.25) *c _(p) ¹*μ^(−0.25).Case 2

In the electric vehicle design addressed in this Case 2, there is alarge surface area across which heat is removed from hot surfaces. Thisis the case when, for instance, the battery to be cooled has a largesurface area available for cooling. As a result, the amount of heat flowfrom the hot surface to the heat transfer fluid is heat conveyancedominated. In the vehicle design addressed in this Case 2, the coolingcircuit design produces laminar flow (Reynolds number less than around2100) throughout the system, in order to protect against damage tosensitive components such as electronics and minimize the pressurerequired to circulate the heat transfer fluid. Finally, in the vehicledesign addressed in this Case 2, a constant flow (positive displacement)pump is employed, such that the volume of heat transfer fluid beingpumped through the system is independent of the properties of the heattransfer fluid.

As a result, in this type of electric vehicle, the normalizedeffectiveness factor (NEF_(fluid)) will be proportional to the followingcombination of heat transfer fluid properties:ρ¹ *c _(p) ¹*μ⁻¹.Preparation of Heat Transfer Fluid Formulations and Testing Results

All of the ingredients used in the heat transfer fluid formulations arecommercially available. Heat transfer fluid formulations were preparedas described herein.

Optional additives used in the formulations include conventionaladditives in conventional amounts. Optional additives were one or moreof an antioxidant, corrosion inhibitor, antifoam agent, and antiwearadditive.

Heat transfer fluids were prepared by blending at least one base stock,with one or more additives selected from an antioxidant, corrosioninhibitor, antifoam agent, and antiwear additive.

Density (ρ) was measured in accordance with ASTM D8085 or D4052.Specific heat (C_(p)) was measured by ASTM E1269. Dynamic viscosity (μ)was measured by ASTM D8085 or derived from ASTM D445 and ASTM D4052.

Dimensional effectiveness factor (DEF_(fluid)) equations for situationswhere heat conveyance is the dominant mechanism controlling performanceof the heat transfer fluid in an application are given in Table 1herein.

The normalized effectiveness factor (NEF_(fluid)) was determined by theequation:

${{N\; E\; F_{fluid}} = \frac{{DEF}_{fluid}}{{DEF}_{reference}}};$wherein DEF_(fluid) is a dimensional effectiveness factor for the heattransfer fluid that is determined based on an equation designated inTable 1 herein for a selected pump and a selected cooling circuitdominant flow regime; and wherein DEF_(reference) is a dimensionaleffectiveness factor for a reference fluid that is determined using thesame equation designated in Table 1 for DEF_(fluid) above for the sameselected pump and the same selected cooling circuit dominant flowregime. Both DEF_(fluid) and DEF_(reference) were determined at the samepredetermined temperature (i.e., 40° C. or 80° C.), and matching unitsfor each property were used in each equation.

Formulations and properties, dimensional effectiveness factor(DEF_(fluid)) values, and normalized effectiveness factor (NEF_(fluid))values, for reference fluids and heat transfer fluids at a temperatureof 40° C., where heat conveyance is the dominant mechanism controllingperformance of the reference fluid and heat transfer fluid in anapplication, are shown in FIG. 1.

Formulations and properties, dimensional effectiveness factor(DEF_(fluid)) values, and normalized effectiveness factor (NEF_(fluid))values, for reference fluids and heat transfer fluids at a temperatureof 80° C., where heat conveyance is the dominant mechanism controllingperformance of the reference fluid and heat transfer fluid in anapplication, are shown in FIG. 2.

PCT and EP Clauses:

1. A heat transfer fluid for use in a heat transfer system, said heattransfer fluid comprising:

at least one non-aqueous dielectric heat transfer fluid, saidnon-aqueous dielectric heat transfer fluid having density (ρ), specificheat (c_(p)), and dynamic viscosity (μ) properties;

wherein the heat transfer system comprises an apparatus and a heattransfer circuit, where said heat transfer circuit comprises:

-   -   a pump,    -   a conduit, and    -   a heat exchanger;

wherein the pump is at least one pump selected from the group consistingof: a positive displacement pump and a centrifugal pump;

wherein the heat transfer fluid circulating through the heat transfercircuit has a heat transfer circuit dominant flow regime selected fromthe group consisting of: laminar flow and transition flow;

wherein the heat transfer system is heat conveyance dominated; and

wherein the heat transfer fluid has a normalized effectiveness factor(NEF_(fluid)) as determined by the following equation:

${{N\; E\; F_{fluid}} = \frac{{DEF}_{fluid}}{{DEF}_{reference}}};$

wherein DEF_(fluid) is a dimensional effectiveness factor for the heattransfer fluid that is determined based on an equation designated inTable 1 below for a selected pump and a selected heat transfer circuitdominant flow regime;

wherein DEF_(reference) is a dimensional effectiveness factor for areference fluid that is determined using the same equation designated inTable 1 for DEF_(fluid) above for the same selected pump and the sameselected heat transfer circuit dominant flow regime;

wherein DEF_(fluid) and DEF_(reference) are determined at apredetermined temperature in an apparatus heat transfer application, andmatching units for each property are used in each equation; and

TABLE 1 (Heat Transfer Fluid and Reference Fluid) Selected Heat TransferCircuit Flow Regime Transition Selected Pump Laminar (Blasius) PositiveDisplacement Pump ρ¹ c_(p) ¹ μ⁻¹ ρ^(0.25) c_(p) ¹ μ^(−0.25) CentrifugalPump ρ^(0.19) c_(p) ¹ μ^(−0.19) ρ^(0.04) c_(p) ¹ μ^(−0.04)

wherein the heat transfer fluid has a NEF_(fluid) value equal to orgreater than 1.0.

2. The heat transfer fluid of clause 1 having a NEF_(fluid) value fromequal to or greater than 1.0 to about 1.5.

3. The heat transfer fluid of clauses 1 and 2 wherein the predeterminedtemperature is the mean heat transfer fluid temperature in an apparatusheat transfer application.

4. The heat transfer fluid of clauses 1 and 2 wherein the predeterminedtemperature is between about −40° C. and about 125° C.

5. The heat transfer fluid of clauses 1-4 wherein the apparatus is anelectrical apparatus.

6. The heat transfer fluid of clauses 1-5 which is at least one fluidselected from the group consisting of a Group I base oil, Group II baseoil, Group III base oil, Group IV base oil, and Group V base oil.

7. The heat transfer fluid of clauses 1-5 which is at least one fluidselected from the group consisting of an aromatic hydrocarbon,polyolefin, paraffin, isoparaffin, ester, ether, fluorinated fluid, nanofluid, and silicone oil.

8. The heat transfer fluid of clauses 1-5 which is a polyolefin.

9. The heat transfer fluid of clauses 1-8 wherein the reference fluid isat least one fluid selected from the group consisting of biphenyl26.5%+diphenyl oxide 73.5%, siloxane (>95%, KV100 16.6 cSt),organosilicate ester (>90%, KV100 0.93 cSt), organosilicate ester (>90%,KV100 1.6 cSt), perfluoro fluid C5-C8 (KV25 2.2 cSt), and3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethyl-hexane(>99%).

10. The heat transfer fluid of clauses 1-9 which further comprises oneor more additives.

11. The heat transfer fluid of clause 10 wherein the one or moreadditives is at least one additive selected from the group consisting ofan antioxidant, a corrosion inhibitor, an antifoam agent, an antiwearadditive, nanomaterials, nanoparticles, and combinations thereof.

12. The heat transfer fluid of clauses 1-11 wherein the apparatuscomprises an electric vehicle, a computer server farm, a chargingstation, or a rechargeable battery system.

13. A method for improving performance of a heat transfer system, saidmethod comprising:

(i) providing an apparatus having a heat transfer system, said heattransfer system comprising a heat transfer circuit, where said heattransfer circuit comprises:

-   -   a pump,    -   a conduit, and    -   a heat exchanger;

wherein the pump is at least one pump selected from the group consistingof: a positive displacement pump and a centrifugal pump;

(ii) circulating at least one non-aqueous dielectric heat transfer fluidthrough the heat transfer circuit to transfer heat with the apparatus,said non-aqueous dielectric heat transfer fluid having density (ρ),specific heat (c_(p)), and dynamic viscosity (μ) properties;

wherein the heat transfer fluid circulating through the heat transfercircuit has a heat transfer circuit dominant flow regime selected fromthe group consisting of: laminar flow and transition flow;

wherein the heat transfer system is heat conveyance dominated; and

(iii) determining a normalized effectiveness factor (NEF_(fluid)) of theheat transfer fluid from the following equation:

${{N\; E\; F_{fluid}} = \frac{{DEF}_{fluid}}{{DEF}_{reference}}};$

wherein DEF_(fluid) is a dimensional effectiveness factor for the heattransfer fluid that is determined based on an equation designated inTable 1 below for a selected pump and a selected heat transfer circuitdominant flow regime;

wherein DEF_(reference) is a dimensional effectiveness factor for areference fluid that is determined using the same equation designated inTable 1 for DEF_(fluid) above for the same selected pump and the sameselected heat transfer circuit dominant flow regime;

wherein DEF_(fluid) and DEF_(reference) are determined at apredetermined temperature in an apparatus heat transfer application, andmatching units for each property are used in each equation; and

TABLE 1 (Heat Transfer Fluid and Reference Fluid) Selected Heat TransferCircuit Flow Regime Transition Selected Pump Laminar (Blasius) PositiveDisplacement Pump ρ¹ c_(p) ¹ μ⁻¹ ρ^(0.25) c_(p) ¹ μ^(−0.25) CentrifugalPump ρ^(0.19) c_(p) ¹ μ^(−0.19) ρ^(0.04) c_(p) ¹ μ^(−0.04)

whereby performance of the heat transfer system during operation isimproved using a heat transfer fluid having a NEF_(fluid) value equal toor greater than 1.0.

14. A method for improving performance of an apparatus, said methodcomprising:

(i) providing an apparatus having a heat transfer system, said heattransfer system comprising a heat transfer circuit, where said heattransfer circuit comprises:

-   -   a pump,    -   a conduit, and    -   a heat exchanger;

wherein the pump is at least one pump selected from the group consistingof: a positive displacement pump and a centrifugal pump;

(ii) circulating at least one non-aqueous dielectric heat transfer fluidthrough the heat transfer circuit to transfer heat with the apparatus,said non-aqueous dielectric heat transfer fluid having density (ρ),specific heat (c_(p)), and dynamic viscosity (μ) properties;

wherein the heat transfer fluid circulating through the heat transfercircuit has a heat transfer circuit dominant flow regime selected fromthe group consisting of: laminar flow and transition flow;

wherein the heat transfer system is heat conveyance dominated; and

(iii) determining a normalized effectiveness factor (NEF_(fluid)) of theheat transfer fluid from the following equation:

${{N\; E\; F_{fluid}} = \frac{{DEF}_{fluid}}{{DEF}_{reference}}};$

wherein DEF_(fluid) is a dimensional effectiveness factor for the heattransfer fluid that is determined based on an equation designated inTable 1 below for a selected pump and a selected heat transfer circuitdominant flow regime;

wherein DEF_(reference) is a dimensional effectiveness factor for areference fluid that is determined using the same equation designated inTable 1 for DEF_(fluid) above for the same selected pump and the sameselected heat transfer circuit dominant flow regime;

wherein DEF_(fluid) and DEF_(reference) are determined at apredetermined temperature in an apparatus heat transfer application, andmatching units for each property are used in each equation; and

TABLE 1 (Heat Transfer Fluid and Reference Fluid) Selected Heat TransferCircuit Flow Regime Transition Selected Pump Laminar (Blasius) PositiveDisplacement Pump ρ¹ c_(p) ¹ μ⁻¹ ρ^(0.25) c_(p) ¹ μ^(−0.25) CentrifugalPump ρ^(0.19) c_(p) ¹ μ^(−0.19) ρ^(0.04) c_(p) ¹ μ^(−0.04)

whereby performance of the apparatus during operation is improved usinga heat transfer fluid having a NEF_(fluid) value equal to or greaterthan 1.0.

15. A method for selecting a heat transfer fluid for use in a heattransfer system, said method comprising:

(i) providing an apparatus having a heat transfer system, said heattransfer system comprising a heat transfer circuit, where said heattransfer circuit comprises:

-   -   a pump,    -   a conduit, and    -   a heat exchanger;

(ii) circulating at least one non-aqueous dielectric heat transfer fluidthrough the heat transfer circuit to transfer heat with the apparatus,said non-aqueous dielectric heat transfer fluid having density (ρ),specific heat (c_(p)), and dynamic viscosity (μ) properties;

(iii) selecting a type of pump used in the heat transfer circuit,wherein the pump is at least one pump selected from the group consistingof: a positive displacement pump and a centrifugal pump;

(iv) selecting a heat transfer circuit dominant flow regime used tocirculate the heat transfer fluid through the heat transfer circuit;wherein the heat transfer circuit dominant flow regime is selected fromthe group consisting of: laminar flow and transition flow;

(v) conducting the heat transfer system such that it is heat conveyancedominated;

(vi) determining a normalized effectiveness factor (NEF_(fluid)) for theheat transfer fluid from the following equation:

${{N\; E\; F_{fluid}} = \frac{{DEF}_{fluid}}{{DEF}_{reference}}};$

wherein DEF_(fluid) is a dimensional effectiveness factor for the heattransfer fluid that is determined based on an equation designated inTable 1 below for the selected pump and the selected heat transfercircuit dominant flow regime;

wherein DEF_(reference) is a dimensional effectiveness factor for areference fluid that is determined using the same equation designated inTable 1 for DEF_(fluid) above for the same selected pump and the sameselected heat transfer circuit dominant flow regime;

wherein DEF_(fluid) and DEF_(reference) are determined at apredetermined temperature in an apparatus heat transfer application, andmatching units for each property are used in each equation; and

TABLE 1 (Heat Transfer Fluid and Reference Fluid) Selected Heat TransferCircuit Flow Regime Transition Selected Pump Laminar (Blasius) PositiveDisplacement Pump ρ¹ c_(p) ¹ μ⁻¹ ρ^(0.25) c_(p) ¹ μ^(−0.25) CentrifugalPump ρ^(0.19) c_(p) ¹ μ^(−0.19) ρ^(0.04) c_(p) ¹ μ^(−0.04)

(vii) selecting the heat transfer fluid for use in the heat transfersystem if the NEF_(fluid) for the heat transfer fluid is a value equalto or greater than 1.0.

All patents and patent applications, test procedures (such as ASTMmethods, UL methods, and the like), and other documents cited herein arefully incorporated by reference to the extent such disclosure is notinconsistent with this disclosure and for all jurisdictions in whichsuch incorporation is permitted.

When numerical lower limits and numerical upper limits are listedherein, ranges from any lower limit to any upper limit are contemplated.While the illustrative embodiments of the disclosure have been describedwith particularity, it will be understood that various othermodifications will be apparent to and can be readily made by thoseskilled in the art without departing from the spirit and scope of thedisclosure. Accordingly, it is not intended that the scope of the claimsappended hereto be limited to the examples and descriptions set forthherein but rather that the claims be construed as encompassing all thefeatures of patentable novelty which reside in the present disclosure,including all features which would be treated as equivalents thereof bythose skilled in the art to which the disclosure pertains.

The present disclosure has been described above with reference tonumerous embodiments and specific examples. Many variations will suggestthemselves to those skilled in this art in light of the above detaileddescription. All such obvious variations are within the full intendedscope of the appended claims.

What is claimed is:
 1. A heat transfer fluid for use in a heat transfersystem, said heat transfer fluid comprising: at least one non-aqueousdielectric heat transfer fluid, said non-aqueous dielectric heattransfer fluid having density (ρ), specific heat (c_(p)), and dynamicviscosity (μ) properties; wherein the heat transfer system comprises anapparatus and a heat transfer circuit, where said heat transfer circuitcomprises: a pump, a conduit, and a heat exchanger; wherein the pump isat least one pump selected from the group consisting of: a positivedisplacement pump and a centrifugal pump; wherein the heat transferfluid circulating through the heat transfer circuit has a heat transfercircuit dominant flow regime selected from the group consisting of:laminar flow and transition flow; wherein the heat transfer system isheat conveyance dominated; and wherein the heat transfer fluid has anormalized effectiveness factor (NEF_(fluid)) as determined by thefollowing equation:${{N\; E\; F_{fluid}} = \frac{{DEF}_{fluid}}{{DEF}_{reference}}};$wherein DEF_(fluid) is a dimensional effectiveness factor for the heattransfer fluid that is determined based on an equation designated inTable 1 below for a selected pump and a selected heat transfer circuitdominant flow regime; wherein DEF_(reference) is a dimensionaleffectiveness factor for a reference fluid that is determined using thesame equation designated in Table 1 for DEF_(fluid) above for the sameselected pump and the same selected heat transfer circuit dominant flowregime; wherein DEF_(fluid) and DEF_(reference) are determined at apredetermined temperature in an apparatus heat transfer application, andmatching units for each property are used in each equation; and TABLE 1(Heat Transfer Fluid and Reference Fluid) Selected Heat Transfer CircuitFlow Regime Transition Selected Pump Laminar (Blasius) PositiveDisplacement Pump ρ¹ c_(p) ¹ μ⁻¹ ρ^(0.25) c_(p) ¹ μ^(−0.25) CentrifugalPump ρ^(0.19) c_(p) ¹ μ^(−0.19) ρ^(0.04) c_(p) ¹ μ^(−0.04)

wherein the heat transfer fluid has a NEF_(fluid) value equal to orgreater than 1.0.
 2. The heat transfer fluid of claim 1 wherein thepredetermined temperature is the mean heat transfer fluid temperature inan apparatus heat transfer application.
 3. The heat transfer fluid ofclaim 1 wherein the predetermined temperature is between about −40° C.and about 125° C.
 4. The heat transfer fluid of claim 1 wherein theapparatus is an electrical apparatus.
 5. The heat transfer fluid ofclaim 1 which is at least one fluid selected from the group consistingof a Group I base oil, Group II base oil, Group III base oil, Group IVbase oil, and Group V base oil.
 6. The heat transfer fluid of claim 1which is at least one fluid selected from the group consisting of anaromatic hydrocarbon, polyolefin, paraffin, isoparaffin, ester, ether,fluorinated fluid, nano fluid, and silicone oil.
 7. The heat transferfluid of claim 1 which further comprises one or more additives.
 8. Theheat transfer fluid of claim 7 wherein the one or more additives is atleast one additive selected from the group consisting of an antioxidant,a corrosion inhibitor, an antifoam agent, an antiwear additive,nanomaterials, nanoparticles, and combinations thereof.
 9. The heattransfer fluid of claim 1 wherein the reference fluid is at least onefluid selected from the group consisting of biphenyl 26.5%+diphenyloxide 73.5%, siloxane (>95%, KV100 16.6 cSt), organosilicate ester(>90%, KV100 0.93 cSt), organosilicate ester (>90%, KV100 1.6 cSt),perfluoro fluid C5-C8 (KV25 2.2 cSt), and3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethyl-hexane(>99%).
 10. The heat transfer fluid of claim 9 wherein the referencefluid comprises biphenyl 26.5%+diphenyl oxide 73.5%.
 11. The heattransfer fluid of claim 1 wherein the apparatus comprises an electricvehicle, a computer server farm, a charging station, or a rechargeablebattery system.
 12. The heat transfer fluid of claim 1 wherein theapparatus comprises an electric motor, generator, rechargeable battery,AC-DC/DC-AC/AC-AC/DC-DC converter, transformer, power management system,electronics controlling a battery, on-board power electronics, superfast charging system, fast charging equipment at a charging station,stationary super fast charger, or on-board charger.
 13. The heattransfer fluid of claim 1 wherein the dimensional effectiveness factor(DEF_(fluid)) of the heat transfer fluid, the dimensional effectivenessfactor (DEF_(reference)) of the reference fluid, and the normalizedeffectiveness factor (NEF_(fluid)) of the heat transfer fluid, aredetermined by a system having a computer, a processor, a memory, and aprogram module, wherein the program module contains instructions forcontrolling the processor to determine the dimensional effectivenessfactor (DEF_(fluid)) of the heat transfer fluid, the dimensionaleffectiveness factor (DEF_(reference)) of the reference fluid, and thenormalized effectiveness factor (NEF_(fluid)) of the heat transferfluid.
 14. The heat transfer fluid of claim 13 wherein the systemfurther comprises one or more databases configured to store and arrangedata in said memory and to interact with the processor, the datacomprising at least one fluid property selected from the groupconsisting of density (ρ), specific heat (c_(p)), thermal conductivity(k), and dynamic viscosity (μ).
 15. An apparatus having a heat transfersystem, wherein at least one heat transfer fluid of claim 1 iscirculated in the heat transfer system.
 16. An electric vehicle having aheat transfer system, wherein at least one heat transfer fluid of claim1 is circulated in the heat transfer system.